Frequently Asked Questions about the Corona-Warn-App

Support

Who can help with questions regarding the Corona-Warn-App?

The technical hotline (click here to see the phone numbers) will help you with technical questions about the Corona-Warn-App, for instance if you have problems with exposure logging. You can reach the technical hotline from Monday to Saturday from 7 a.m. to 10 p.m. (except on German national holidays), and it is free of charge for you within Germany.

The TAN hotline (click here to see the phone numbers) will help you to enter the TAN if you have a positive test result and if you have not received a TAN or document with a PCR-Test QR code. The TAN hotline is available 24 hours a day, seven days a week. The call is free of charge from within Germany.

If the test result is not available in the Corona-Warn-App, the relevant service personnel, test centre or health authority should be contacted to obtain the test result.
In order to make it easier for you to find the responsible health authority, the RKI has provided a corresponding tool. By entering the postal code or the city of residence, the responsible health authority (including contact details) is immediately displayed: Robert Koch Institute Tool: Health authority by postal code or place

Further information on the PCR-Test QR Code procedure can be found in this FAQ entry: I have scanned a PCR-Test QR code, but the test result could not be retrieved for days.

The websites of the Federal Government are offering general information and videos: https://www.bundesregierung.de/breg-de/themen/corona-warn-app/corona-warn-app-englisch.

The Robert Koch Institute also provides information on epidemiological aspects: https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/nCoV_node.html (German only).

As a media representative, please direct your enquiries to press@sap.com.

The various feedback channels of the Corona-Warn-App-Community will help you with your questions about the open source project of the Corona-Warn-App.

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How to reach us

You can reach us by phone from within Germany and from abroad. The national numbers are free of charge, but are only available from within Germany. The international numbers are not free of charge - the cost of the international call is based on the contract with your provider.

Technical Hotline

The technical hotline will help you with technical questions about the Corona-Warn-App, for instance if you have problems with the exposure logging. It is available Monday to Saturday from 7 a.m. to 10 p.m. German local time (except on national holidays)

National: 0800 7540001

International: +49 30 498 75401

TAN Hotline

The TAN hotline will help you to enter the TAN if you have a positive test result and if you have not received a TAN or document with a PCR-Test QR code. The TAN hotline is available 24 hours a day, seven days a week.

National: 0800 7540002

International: +49 30 498 75402

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How do I create an error report?

With version 2.2, the Corona-Warn-App (CWA) offers a new function for detailed technical problem analysis. The error report is intended to help the developers to perform a root cause analysis faster and to eliminate errors more efficiently.
Important: Please report an issue to the technical support first, either by phone (click here to see the phone numbers) or by e-mail (corona-warn-app.opensource@sap.com), to verify if there is already a known solution. An error report is only required if the technical support asks for this report.

The best place to share the unique report ID is where it was requested. You can also share the ID in the following ways:

• Open an issue on GitHub (Android or iOS) and mention the ID of your error report
• Share the ID with the technical support
• Write a review on the Corona-Warn-App in the Apple App Store or Google Play Store and mention the ID of your error report

Regardless of which contact option you choose, the following tips will help to resolve your issue as quickly as possible:

1. Describe the problem as accurately as possible
2. Start the error analysis in the CWA (see blog post)
   • Try to reproduce the incorrect behaviour or to generate the error message
   • If this is successful, send the error report to the CWA server. The data will be anonymized and encrypted
   • You can then find your unique ID on the bottom of the 'Error Reports' screen, scroll down and click on 'ID History'
3. Stop the error analysis
4. Share the 'unique report ID' with the technical support

Notes:

• The error reports are automatically deleted after 14 days
• Error reports that are transmitted to the server without request by the technical support cannot be analyzed and processed
• There is no direct feedback channel for the error reports in the Corona-Warn-App. Technical support can only communicate with you via one of the above mentioned channels

For more info as well as screenshots, see the blog article Corona-Warn-App version 2.2 enables creation of a rapid test profile and error reports

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Where can I get tested?

Rapid antigen test sites connected to the Corona-Warn-App are offered by the following partners:

• Appointments can be booked in advance via their websites:
  • Bavarian Red Cross
  • dm-drogerie markt
  • EcoCare (Kaufland und Lidl)
  • No-Q (participating pharmacies, family doctors and other test centers)

• Without central website for booking appointments:
  • Doctorbox
  • Huber Health Care

• Appointments only for their own employees:
  • The Federal Chancellery tests its own employees
  • Saarland's Ministry of Education and Culture tests teachers

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An overview of the PCR and rapid antigen test sites can be found on this BMG webpage (not clear whether the test site is connected to the CWA or not).

Another list of test sites from the Github community: Where to get tested?

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News

Information about the security vulnerability already fixed by Google in the Exposure Notification Framework

On April 27, 2021, reports appeared that a vulnerability in the Exposure Notification Framework (ENF) in the Android operating system was announced. This vulnerability allowed pre-installed apps on Android smartphones to access system log files, thus reading ENF data that is also provided by the Corona-Warn-App (CWA). Google has provided a fix for Android, and says that it has now been rolled out up to 98%. All Android versions that use the Google Play Services below version 21.15 are affected.

All risks associated with using the CWA are described in the Privacy Impact Assessment (risk details can be found in Appendix 6, Section 4).

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Data donation and event-based scientific survey

More information on the topics of data donation by the user and event-based scientific survey can be found in this blog entry:

Users can provide data voluntarily to help improve the Corona-Warn-App further .

Further details regarding data protection can be found on this poster:

Evaluation of the Corona-Warn-App: How user privacy remains protected.

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In-App statistics starting with release 1.11

Due to the high dynamics of the pandemic, the Corona-Warn-App displays important statistical key figures on current infections starting with the 1.11 version of the app. The figures displayed guide users to better assess the current situation and to adjust their own behaviour.

The number of new infections is published once a day by the Robert Koch Institute (RKI). 'Yesterday' means that the value considers all reported new infections from the previous day until 23:59.

The statistics displayed in the Corona-Warn-App are compiled from different sources and are formatted for the app about every 15 minutes. Besides the aggregated numbers from the previous day (e.g. reported new infections), the statistics also show the R-value, which is an estimate for the current day based on the "nowcasting" approach.

The concept of the R-value and the data basis of its calculation is described in detail in the Epidemiological Bulletin of the RKI (#17/2020 of 04/23/2020). Sample calculations and the daily updated R-values (4-day and 7-day R-value) are available as an Excel table at http://www.rki.de/covid-19-nowcasting.

To ensure the validity of the data in the CWA's statistics, all data sources are carefully verified for completeness and consistency. Thus, the presentation of the data in the app may be slightly delayed in comparison to other websites/sources. However, in terms of content, the values correspond to the official case numbers of the RKI.

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Vaccination Cert.

Questions and answers about the vaccination certificate

• Can I save my vaccination certificate on multiple smartphones, e.g., on my private and business phone?
• How can I transfer the vaccination certificate when changing device?
• What do I do if I lose my phone?
• Will the vaccination certificate be included in my backup?
• Can I manage the certificate in the Corona-Warn-App and the CovPass-App at the same time, or do I have to choose one of the two apps?

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Why do I get the error message 'This QR code is not a valid vaccination certificate. (VC_PREFIX_INVALID)' when I try to scan my vaccination QR code?

As of 14 June 2021: Since 14 June 2021 certificates with QR codes, which can be scanned with the app, are being issued in vaccination centers.

Usually, any document issued before 14 June 2021 will not be a valid digital EU vaccination certificate, but just a vaccination documentation according to §22 of the German Infection Protection Act, that is incompatible with the latest aligned European guidelines for a digital vaccination certificate. Therefore, such a document, as well as the barcodes and QR codes in the yellow vaccination booklet, cannot be scanned with the Corona-Warn-App.

The new digital certificate statements (that can be scanned) are in the process of being made available by authorized agencies. In some federal states, vaccination centers will automatically send these new digital certificates via mail. Starting on 14 June 2021, those who have already been vaccinated can have the digital vaccination certificate issued in pharmacies on the basis of a vaccination record (yellow vaccination booklet or vaccination proof), if they do not receive a digital certificate via mail. Pharmacies search.

In this news article you will find information about the individual federal states:
Digitaler Corona-Impfpass startet - das ist der Stand in Ihrem Bundesland.

Example of EU Digital COVID Vaccination Certificate:

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What is the digital certificate of vaccination?

Starting with version 2.3 of the Corona-Warn-App (CWA), you can add your digital vaccination certificate to the CWA and thus securely and digitally prove your Corona vaccination status via QR code. The CWA indicates the complete vaccination protection 14 days after the last required vaccination. The digital vaccination certificate is an additional way to document vaccinations. Thereby you are able to digitally store information such as vaccination time and vaccine in a personalized manner on your smartphones. The use of digital certificate of vaccination in the CWA is voluntary. You can also prove your Corona vaccination in a different way.

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Why is there a digital proof of vaccination?

At the beginning of the year, the European Council decided to launch an interoperable and standardized proof of vaccination for medical purposes. Germany is now quickly implementing this European decision in order to be able to provide all citizens who wish to do so with a digital proof of vaccination. In the meantime, the European Commission has also presented a draft regulation regulating an EU-wide recognition framework for (digital) certificates for vaccinations, tests and for persons with COVID-19 recovered status in order to facilitate the free movement of travelers. The EU's Digital COVID Certificate forms the legal framework for the member states' solutions.

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Who can obtain an digital proof of vaccination? How do I get a vaccination certificate? If I already have full vaccination protection, how can I transfer the status to the Corona-Warn-App afterwards?

All persons who are entitled to a vaccination may also have a digital proof of vaccination available in addition to the paper-based vaccination certificate.

If necessary, you can obtain a Corona vaccination certificate from the doctor's office or vaccination center where the vaccination was carried out. Simply ask on site. However, vaccination centers and medical practices are not obliged to issue vaccination certificates.

Various ways are being explored to create digital vaccination certificates for Corona vaccinations afterwards. In principle, the subsequent issuance should take place where one has been vaccinated. If the appropriate contact details are available in the vaccination centers, the QR codes should be sent automatically by mail as far as possible. In addition, doctors and pharmacists could subsequently provide proof of vaccination.

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Can I use a complete vaccination status in the app as a travel permission?

For example, whether you are allowed to travel with completed vaccination protection, depends on the regulations of the respective country.

Among other things, you can use this tool in order to plan your journey within the EU.

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How does digital proof of vaccination work?

The digital proof of vaccination is generated in the doctor's pratice or in a vaccination center. After entering or transferring the data, a vaccination certificate token (QR code) will be created for you, which you can scan directly with the Corona-Warn-App (CWA) or can be handed to you on a paper printout and later scanned with the CWA. You can then manage your digital vaccination certificates on your smartphone.

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Can I show the QR code without an internet connection?

Yes. As soon as the QR code is displayed in the Corona-Warn-App, you can show it at any time without being connected to the internet.

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Am I obliged to use the digital certificate of vaccination in the Corona-Warn-App? Will there still be the yellow paper-based vaccination booklet? Can I continue to use my yellow vaccination booklet? What about people who don't own a smartphone?

The digital proof of vaccination via the Corona-Warn-App is a completely voluntary and complementary offer. If you do not have a digital certificate of vaccination or have lost it, the proof of vaccination via the well-known 'yellow booklet' (yellow vaccination passport) is still possible and valid. You can also prove Corona vaccinations with the printed Corona vaccination certificate for full vaccination.

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How is the proof of vaccination verified?

The vaccination certificate (QR code) is used digitally via the CovPass-App or the Corona-Warn-App (CWA) or alternatively as a machine-readable print. The vaccination certificate contains only information about the vaccination status, the name of the vaccinated person, and the date of birth. For service providers who want to check the vaccination status, there will be a verification app to check the vaccination certificate. This allows the vaccination status to be scanned in a similar way to a barcode of a flight or train ticket. Alternatively, proof with the paper-based vaccination document is possible.

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Why has no joint EU-wide project been called out for proposal for a certificate?

A joint EU call for proposals would have taken too much time and would have been difficult to implement due to the different vaccination information systems in the Member States. The EU approach is about regulating a recognition framework. Any cross-border pilots could be accompanied by the EU Commission. When implementing the Digital Proof of Vaccination in Germany, the EU requirements have been taken into account from the outset.

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Does my vaccination status affect the calculation of the risk? Does the calculation of the risk change if a vaccinated person has become infected, and then warns other users?

Risk calculation and vaccination certificates are independent features of the app. The risk calculation does not take into account whether you are vaccinated against COVID-19. The calculation of the risk also does not change if a vaccinated person has become infected, and then warns other users.

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How to behave if I am partially or completely vaccinated, but receive a red warning in the Corona-Warn-App?

Recommendation: If a vaccinated person receives a high risk warning, no quarantine is necessary initially, as long as no symptoms appear. If symptoms do occur, you should get tested immediately and go into immediate quarantine.

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Can I save my vaccination certificate on multiple smartphones, e.g., on my private and business phone? How can I transfer the vaccination certificate when changing device? What do I do if I lose my phone? Can I manage the certificate in the Corona-Warn-App and the CovPass-App at the same time, or do I have to choose one of the two apps? Will the vaccination certificate be included in my backup?

There is no limit to how often you can scan the QR code of your vaccination certificates. By scanning the QR code of your certificate you can add and manage the vaccination certificates:

• on multiple devices, e.g. on your private and business phone
• on a new device, when changing device
• in several apps, e.g. the Corona-Warn-App and the CovPass-App
• on a device you have reset. The certificate is not included in the backup.

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Can I save the vaccination certificates of relatives, such as children, in the Corona-Warn-App?

With the Corona-Warn-App, you can only scan and add vaccination certificates from one person. It is not possible to add your own and additionally, for example, that of your child or partner.
With the CovPass-App, the digital vaccination certificates of children or partners can be stored together on a smartphone.

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What data is displayed when checking the QR code?

The QR code is displayed in the Corona-Warn-App. After scanning the QR code with the CovPassCheck-App, only the most necessary information can be seen: vaccination status, last name, first name and date of birth of the vaccinated person.

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Where is my personal data of the digital certificate of vaccination stored? Is there a central vaccination register?

No, there is no central vaccination register. When the Corona vaccination certificate is created, your data will be collected once by the vaccination site and transmitted to the RKI for signing. The data will be deleted there immediately. When you add the Corona vaccination certificate in the app, your personal information is only stored locally (decentralized) on your smartphone. You can decide for yourself if and when to delete this data on your device.

All digital vaccination certificates are created only temporarily in the vaccination logging system and then deleted. Permanent storage is only realized decentral on the users' smartphones.

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How is abuse being prevented?

The QR code for digital certificate of vaccination may only be issued by authorized persons in vaccination centers, medical practices and hospitals. When reviewing digital vaccination certificates, a photo ID may be presented as appropriate. The digital proof of vaccination is cryptographically protected against changes.

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Rapid Antigen Test

Which partners participate in the rapid test integration? Which partners can I book a rapid antigen test with?

See Where can I get tested?

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Why are quick tests now integrated?

In version 2.1 of the Corona-Warn-App, the project team from Deutsche Telekom and SAP has, as announced, integrated rapid tests so that chains of infection can be interrupted even faster.

While PCR test results are only available and can be shared a day later, users can share positive rapid test results shortly after the test. This means that contacts are warned more quickly and chains of infection are broken more quickly.

A negative test result can also be used by users as evidence of a negative rapid test result, if required by law. However, the recognition of test evidence may vary from state to state. Users should therefore inform themselves about the respective criteria in their federal state.

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How do I get my rapid antigen test result?

From the 'Register your Test' section on the home screen of your Corona-Warn-App, you can add a test by scanning the Rapid-Test QR code. To get the result in the app as soon as possible, you can refresh the test in the app until the result is available. Although the Corona-Warn-App also retrieves test results automatically in the background, it may take a little longer depending on your operating system.

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How long is a rapid antigen test valid?

A negative rapid test result is valid for 48 hours after submission and can be used as evidence, if required by law. When you tap on your negative test result on the main screen of the app, under Android, you will see a counter that shows how long your test result has already been available. Under iOS, the date and time when the test result was issued is shown. After 48 hours, your rapid test result will automatically be removed. You can then take another rapid test and register it in the app.

There is no limited validity for positive rapid test results, so no counter or the date of issue will be displayed to you in this case. As soon as you receive a positive test result, immediately follow the instructions displayed in the app.

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What privileges derive from a negative rapid test result? Can I use my test result in the app as proof of admission to shops or visiting hair salons, leisure activities, etc.?

A negative test result can serve as proof of the existence of a negative rapid test result for you, if specified by law. However, the recognition of test evidence may vary from state to state. You should therefore inform yourself about the respective criteria in your federal state.

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How do I act if my rapid test result is positive?

In case of a positive test result, you should share your test result and immediately take a PCR test to confirm or revise the result. In case of a positive PCR test, you should share the test result again to alert contacts you may have met between the two tests. This is provided that the contacts also use the Corona-Warn-App and the risk calculation determines a high risk, based on duration and distance of contact. If the PCR test is negative, you will not have the option to withdraw your positive rapid test and warning.

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If I see a high-risk encounter in the App, i.e. a red card, should I do a rapid antigen test or PCR-Test?

If the Corona-Warn-App shows you an encounter with increased risk (red tile), you should take a PCR test and quarantine yourself.

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Are rapid antigen and PCR tests treated differently in the App?

The rapid test is treated equally to the PCR test by the Corona-Warn-App. If you get tested at one of the Corona-Warn-App partners, you will receive your test result via Rapid-Test QR code, which you can scan with the Corona-Warn-App. A negative test result will then be displayed in the Corona-Warn-App for 48 hours.

In case of a positive test result, you can warn other people within the shortest possible time by sharing your result - as with a PCR test - and uploading it to the Corona-Warn-App server. The positive test result will be displayed in the app until you share it. If you were previously checked in to an event or location via Event Registration, you can share the positive test result along with your check-ins.

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Are warnings from a rapid antigen or PCR test differentiated?

Contact persons receive a warning in their Corona-Warn-App about an encounter on a day with low (green tile) or increased risk (red tile). Whether the warning was based on a rapid test or on a PCR test is not displayed in the app.

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EFGS integration? Are positive results shared in other countries?

Warnings based on a rapid test result are not shared with other EU countries via the EFGS (European Federation Gateway Service), including Switzerland, as the EFGS terms of use do not provide for rapid test warnings to be shared.

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What is the difference between PCR tests, rapid antigen tests and self-tests?

PCR tests are the 'gold standard' among corona tests. Sampling is performed by medical personnel - evaluation by laboratories.

Rapid antigen tests: Have their name because the result is available quickly. They can only be performed by trained personnel. Similar to the PCR test, a nasal or throat swab is taken. However, in contrast to the PCR test, the evaluation takes place directly on site. Since March 8, 2021, everyone is entitled to at least one rapid test per week.

Self-tests: Have their name because anyone can do these tests themselves, for example at home. The self-tests are intended for use by private individuals. For this purpose, sample collection and evaluation must be appropriately simple. The test can be performed with a nasal swab or saliva, for example. The Federal Institute for Drugs and Medical Devices, together with the Paul Ehrlich Institute, checks the quality and significance of the tests.

Rapid and self-tests have a higher error rate compared to PCR tests. Therefore, after each positive rapid and self-test, a PCR test should always be done for confirmation.

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Can I share my positive rapid antigen test result via the TAN hotline?

It is not possible to share a positive rapid test result via the TAN hotline. Only rapid test results communicated via the app have been performed according to the dual control principle and by trained personnel, and can therefore be shared.

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Can I save/manage multiple rapid antigen tests?

No, only one rapid test can be registered in the app at a time. A negative rapid test is displayed in the app for 48 hours. After this time you can register a new test. You also have the option to remove the negative rapid test and result, and then register a new rapid test. Positive rapid tests are no longer displayed in the app once they have been shared.

PCR tests are handled independently from rapid tests. This means you can have one PCR test and one rapid test registered in the app at the same time.

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Do the rapid antigen tests have different risk calculation parameters than a PCR tests?

No. For rapid tests as well as for PCR tests, the same criteria for risk calculation apply as before. If you receive a risk warning, you won't see in the app whether it was caused by sharing a quick test or PCR test result. The exact parameters for the calculation can be found in the FAQ article How does the app calculate the risk (version >=1.9).

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What is the purpose of a rapid test profile?

You can create a rapid test profile with your personal data in the form of a QR code. At test sites of participating partners, where you do not have to make an appointment in advance and who do not have their own appointment booking system, only the QR code in the app is scanned and no further registration is required. This speeds up on-site registration. The staff at the test sites needs the personal data in order to forward it to the health authorities in case of a positive test result. For this reason, a comparison with your identity card is always necessary on site. Once created, the profile remains and can be shown again with each test.

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How can I create, edit and remove a rapid test profile?

• Create a rapid test profile: In order to create a rapid test profile, you can click on 'Next Steps' on the main page of their Corona-Warn-App under 'Register Your Test'. There you will find the area 'Create Rapid Test profile'. There you can enter your personal data, such as name, address and telephone number. When everything is entered, you can save the data. The Corona-Warn-App then creates a QR code from the data that you can show at the test sites.
• Remove rapid test profile (iOS): You can remove a rapid test profile by going to your rapid test profile in the rapid test area of the Corona-Warn-App and selecting 'Remove Rapid Test Profile'.
Remove rapid test profile (Android): You can remove a rapid test profile by going to your rapid test profile in the rapid test area of the Corona-Warn-App and selecting 'Remove' in the 3-dot-icon.
• Edit rapid test profile: If you intend to edit a rapid test profile, you can first remove it and then create a new profile.

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Event Check-In

Questions and answers about the event registration

Questions and answers about functionality, misuse, and privacy:

• How does event registration work in the Corona-Warn-App?
• How is the event registration technically implemented?
• For which locations and events is event registration suitable?
• How do I as an event organizer prevent misuse?
• How do I prevent false warnings as an event participant?
• Do I have to worry that the use of the event registration will make my whereabouts or personal data public?

Questions and answers about the Event QR code:

• Who generates the Event QR code?
• Can the Event QR code also be set up and used for a private birthday party, providing this is legally possible?
• Where can the Event QR code be generated?
• Will there be a way to check in without a smartphone (dongle or similar)?
• How should I scan the Event QR code?
• What happens if I scan a Event QR code but do not have the CWA installed on my smartphone?

Questions and answers about the warning:

• What is the procedure in case of a positive result?
• Does everyone who scanned the same Event QR code get a warning?
• What exactly needs to happen in this new feature for users who have checked into a specific location to be warned through the app?
• How is the risk determined?
• When do I receive a low-risk warning (green tile), when do I receive a high-risk warning (red tile)?
• Can the user see what the alert is based on, i.e. which scanned Event QR code caused the warning?
• Can this information be voluntarily communicated to the health authority? If so, what information is flowing?

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How does event registration work in the Corona-Warn-App?

The Corona-Warn-App (CWA) can use Bluetooth Low Energy (BLE) technology to determine a risk of infection if people have had contact up to approximately 1.5 meters apart for at least 10 minutes. However, according to current knowledge, aerosols spread far beyond this distance in poorly ventilated interiors (SARS-CoV-2 transmission by aerosols). Therefore, the risk of infection in these cases is not limited to a distance of 1.5 meters. The risk of getting infected indoors is many times higher than in outdoor areas.

In order to be able to recognize such constellations indoors, the CWA has been extended by event registration. The app also warns people who have been in a room with a SARS-CoV-2 infected person at the same time. Persons register for an event or place by means of the CWA without providing personal data. If a participant of the event or visitor to the place later registers as positively tested via the CWA, all other persons who participated in the same event or visited the same place at the same time can be warned pseudonymously.

To the index of the event registration

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How is the event registration technically implemented?

Presence Tracing - in CWA also referred to as Event Registration - aims at notifying people of a potential SARS-CoV-2 exposure if they have been to the same venue at a similar time as a positively tested individual. It addresses the potential of airborne transmission in spaces with poor ventilation despite maintaining physical distance. As such, it complements BLE-based proximity tracing with the Exposure Notification Framework.

CWA proposes a fully-automated decentral solution for Presence Tracing which works independent of local health authorities and the collaboration of the host of a venue. It integrates into the existing verification processes of CWA to issue warnings. The solution prioritizes the speed of issuing warnings over their accuracy. A higher degree of accuracy would require manual assessment by local health authorities and the respective resources to do so and is currently not in scope. The solution also protects the privacy of both venues and users, as details about a venue such as description or address are not shared with the CWA infrastructure. 

In summary, the proposed solution allows a host to create a venue through CWA. All necessary data about the venue is encoded in an (Event) QR code which can be presented on a mobile device or printed out, for example to be posted at the entrance of the venue. An attendee can check in to the venue by scanning the QR code. Check-ins are stored locally on the mobile device and deleted automatically after two weeks.

When an attendee tests positive for SARS-CoV-2, they can upload their check-ins along with their Diagnosis Keys to the CWA Server. The CWA Server publishes the relevant check-ins on CDN as warnings. Clients regularly download these warnings and match them against the local check-ins on the mobile device. If there is a match and the time an attendee spent at a venue overlaps with a warning for a sufficiently long time, the attendee receives a warning in CWA similar to how warnings are issued for BLE-based exposures.

For more information on the implementation of the check-in feature, see here: https://github.com/corona-warn-app/cwa-documentation/blob/master/event_registration.md.

To the index of the event registration

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For which locations and events is event registration suitable?

The purpose of event registration is to identify risk contacts that are currently not detected with Bluetooth-Low-Energy Technology (BLE). The scope of application is therefore primarily geared to indoor use, where there is an increased risk of infection due to the distribution of aerosols in the room, even beyond the usual contact limit of 1.5 meters. Ideally, a separate Event QR code should be created for each room where visitors are staying. Each visitor then scans the QR code for the rooms in which she/he has stayed. This ensures that only those who have been exposed to an increased risk of infection are warned.

The QR code for an event is tied to the venue. The QR code should only be accessible to visitors of the event and should therefore not be distributed via digital media.

For outdoor events, the risk of infection is usually limited to a distance of 1.5 meters, which can already be detected with BLE technology, i.e. the usual use of the CWA. Basically, the event registration can be used here as well. However, it is not suitable for events in large outdoor areas, such as zoos.

To the index of the event registration

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How do I as an event organizer prevent misuse?

A common form of misuse of the event registration can be carried out when people check in to an event or place even though they were not present. These individuals would then be warned by CWA if a person who duly checked in at the event would later be tested positive for SARS-CoV 2 and share their positive result via an app. In short, people are being warned even though there is no increased risk to them because they were not there at all. Therefore, some rules should be followed when dealing with your own Event QR codes:

• Only share the QR code with your visitors
• Don't share the QR code via social media or websites
• If you print and display the QR code, then preferably in an area that is only accessible to your visitors
• Renew the QR code regularly, ideally once a day (in the CWA, a QR code can be easily transferred)
• When creating the QR code, provide a meaningful title and exact location. This is the only way to ensure that your visitors check in for the correct event.
• Regularly ensure that the QR code is easy to read and not obscured (e.g., by covering or painting over it)

To the index of the event registration

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How do I prevent false warnings as an event participant?

• Check in only for events or places you visit. Do not scan Event QR codes distributed through digital media or websites
• Check-in to see if the title and location of the event (shown in the app after scanning) match the event you attended
• The more accurately you specify the time of your attendance, the more accurately you can be warned or warn other participants
• Already when checking in, specify as accurately as possible when you want to be checked out automatically. If your stay is shortened or extended, you can also manually correct the time after the automatic check-out has already taken place
• Don't share photographed Event QR codes via social media or other channels

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Do I have to worry that the use of the event registration will make my whereabouts or personal data public?

No, because the essential characteristics of the CWA - decentralization and pseudonymity - are preserved with the event registration. No personal contact details are registered, or location data is transmitted. The data is processed decentrally and pseudonymously on the smartphones.

The Event QR code describes an event with attributes, a detailed address is not required. The QR code is also a random ID that is not processed in the CWA.

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Questions and answers about the Event QR code:

Who generates the Event QR code?

The host of a location or event generates the QR code.

Can the Event QR code also be set up and used for a private birthday party, providing this is legally possible?

Yes of course, that is possible.

Where can the Event QR code be generated?

The QR code can be generated directly in the app and then printed as a PDF or scanned directly from the app.

Will there be a way to check in without a smartphone (dongle or similar)?

No, that is not possible.

How should I scan the Event QR code?

Use only the CWA to scan the QR codes: A QR code can be scanned with the native camera app as well as with the CWA. However, in order to prevent misuse, we recommend the use of the CWA to scan the QR codes. Only the CWA can ensure that legitimate QR codes are processed.

What happens if I scan a Event QR code but do not have the CWA installed on my smartphone?

iOS users are directed to the App Store, where they can download the app. Android users are directed to a website from which they can access the Google Play Store to download the app.

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Questions and answers about the warning:

What is the procedure in case of a positive result?
Does everyone who scanned the same Event QR code get a warning?
What exactly needs to happen in this new feature for users who have checked into a specific location to be warned through the app?

The procedure is based on the existing CWA warning process: If an event participant or a visitor of a location has tested positive, he/she should share this result via the CWA. As a result, all other participants who were checked in at the same time will receive an immediate warning without having to burden the health authorities. Depending on the epidemiological situation, the warning is displayed in one of two versions: 'low risk' (green tile) or 'high risk' (red tile).

How is the risk determined?
When do I receive a low-risk warning (green tile), when do I receive a high-risk warning (red tile)?

The calculation of the risk depends on whether and for how long a user's attendance overlaps with the attendance of a person who later tested positive about COVID-19. If the attendance overlaps by less than 10 minutes, users receive a warning for a low-risk encounter (green tile). If a user's attendance overlaps by 10 minutes or more with that of a person who later tested positive for COVID-19, users will receive a warning about an encounter with increased risk (red tile).

Can the user see what the warning is based on, i.e. which scanned Event QR code caused the warning?

Yes, this is displayed in the contact journal. This allows users to determine, for example, whether other family members that were also present but do not have the app (such as children) were also put at risk.

Can this information be voluntarily communicated to the health authority? If so, what information is flowing?

After a red tile warning (high risk) you should quarantine and have a PCR test taken immediately. If the test result is positive, a report is sent to the health authority by the doctor/test center. It is recommended that you share the positive test result via the CWA. In addition, the information can be also be shared manually with the health department using the existing export function of the contact diary.

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Common Issues

[Apple/iOS]: Why do I see a screen which tells me to update my operating system?

This screen is shown on iPhones running an iOS version between iOS 13.5 and (including) iOS 13.6.1. On these iOS Versions, the necessary version 2 of the Exposure Notification Framework is not available. Therefore you need to update to iOS 13.7 or newer, to continue to use the Corona-Warn-App. More information can be found in this FAQ entry.

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[Google/Android]: Firewall/Router configuration: CAUSE: 4000, error during web request, HTTP status 901

Some firewall settings might prevent the CWA from contacting the Corona-Warn-App backend. This might lead to error notifications, including 'CAUSE: 4000, error during web request, HTTP status 901'. In case you make use of a firewall (router or app), make sure to include the following domains in the access-list for web requests as well as for DNS requests:

• *.coronawarn.app
• *.t-online.de

If you want to allow the usage of the (optional) survey system, you should additionally add these domains to your access-list:

• befragungen.rki.de
• www.howsmyssl.com

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[Google/Android]: Battery optimization is not automatically disabled after activating the prioritized background activity

When you switch on the prioritized background activity on some Android devices, the battery optimization for the Corona-Warn-App is not turned off on OS level. This is a known limitation for a limited number of Android devices. To turn off the battery optimization accordingly, restart your device.

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[Apple/iOS] Can’t enable exposure logging / Empty screen on iOS 13.7/14 / ENA.ExposureNotificationError-Error2

There is a known issue under iOS 13.7 / 14 where in rare cases the Exposure Notifications cannot be activated again after an update. The result is a black screen in the iOS settings.

Also, rare cases (after updates typically) with the error notification 'ENA.ExposureNotificationError-Error2' are known.

To fix the problem, proceed as follows:

1. Navigate to the iOS settings
2. Select 'General' -> 'Reset' -> 'Reset Location and Privacy'
3. Afterwards the permissions in the Corona-Warn-App have to be assigned again. To do so, open the Corona-Warn-App and follow the instructions for the re-assignment of the permissions.

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An encounter has been reported, but the risk status stays green

All active Corona-Warn-Apps regularly download the diagnosis keys released on the Corona-Warn-App server and pass them on to the operating system in batches through an interface. The app checks whether any of these received, recorded rolling proximity identifiers match any of the diagnosis keys. If there is a match, this means the following: The user’s smartphone encountered the smartphone of a person who has subsequently uploaded their diagnosis keys.

In the next step, the app analyzes all the matching rolling proximity identifiers for each diagnosis key, to estimate how long the exposure lasted in total on the day in question and how close the smartphones were to each other on average during the exposure. The distance is calculated from the measured reduction in strength of the Bluetooth signal, which is specified in dB (decibel). All exposures for a diagnosis key that lasted less than 10 minutes (reduced to 5 minutes on Feb 23, 2021, see blog post) in total (regardless of how close the smartphones came during that time) or during which the smartphones were more than 8 meters (73 dB attenuation) apart on average (regardless of how long the exposure lasted) are rated as harmless and are not included in the app's risk calculation.

The remaining encounters are rated collectively according to their distance and duration as well as the presumed infectiousness of the other person(s). This rating doesn't always yield an increased risk. In this case those encounters will be shown in the Corona-Warn-App but the risk status will stay the same.

For more details about risk assessment, including a sample calculation, see https://github.com/corona-warn-app/cwa-documentation/blob/master/cwa-risk-assessment.md.

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[Google/Android]: When activating exposure logging or Bluetooth I'm asked to activate my location. Do I have to do this?

UPDATE
If you are using Android 11 and the Corona-Warn-App version 1.5 or above, you don't have to allow location access in order to use the Corona-Warn-App. This notification is not applicable for Android 11 phones and will be removed in one of the following updates of the Corona-Warn-App.

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Corona-Warn-App does not track your location and does not have permission to do this. The reason for this message is an Android requirement: Bluetooth devices in close proximity to your device can only be detected if 'Use location' is activated on your phone (see Use the COVID-19 Exposure Notifications System on your Android phone and About the Exposure Notifications System and Android location settings in the Android help and Bluetooth Overview in the Android developer documentation). However, this doesn't mean that apps that use Bluetooth can automatically track your location.

Since Corona-Warn-App must be able to detect devices in close proximity, you must activate the general system setting 'Use location'. However: The app will never record your location and will never use GPS. You can verify this yourself:

1. Open 'Settings' on your phone (not the settings of the app).
2. Choose 'Security & Location' > 'Location' > 'App level permissions'.
3. You see a list of apps that can use your location if you give them permission. Corona-Warn-App is not listed here.

Here you can allow or deny other apps to use your location, but since Corona-Warn-App doesn't need this permission, it doesn't even appear in the list.

Again, as described above: You should not deactivate 'Use location' under 'Settings' > 'Security & Location' > 'Location', because this is a prerequisite for exchanging the encrypted random IDs.

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I get an error while scanning the PCR-Test QR code. What can I do?

This problem can have three causes:

The code was already used once for registration

Every PCR-Test QR code you receive can only be entered into the app once. If you use the Corona-Warn-App on multiple devices, the code can only be registered in one device.

If you have already registered the QR code, but then deleted it from the app, the code can also not be entered a second time.

The code you received is designed for another app or service

PCR-Test QR codes for the Corona-Warn-App are distributed on a standardized information sheet as part of form 10C. You can compare the QR code information you received with the bottom half of this example form. If you have not received the depicted information sheet, your QR code is likely incompatible with the app. In this case, please contact the doctor's office or testing center where you made the test and ask them where your QR code can be registered.

The code you received was wrongly generated

In some cases, the error can occur during the first registration of the PCR-Test QR Code. This can happen if a test center generated the QR code in a wrong format. We are currently looking into how to improve the app to detect wrongly generated QR Codes and still accept them. You can find more details about the errors on GitHub.

If you are sure that the QR code was not scanned before and you received the correct information sheet, but are still receiving errors, you can also report this case by mail to corona-warn-app.opensource@sap.com. Please provide a scan of the information sheet with the QR code as well as contact information of the doctor or test center where you received it. All non-essential personal data should be blacked out. We will then try to resolve QR code generation issues together with the involved parties.

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I have scanned a PCR-Test QR code, but the test result could not be retrieved for days.

The processing time of a test (from taking the sample at your doctor's office or test center to the notification in the app) can be up to 48 hours. If you scanned your PCR-Test QR code into the App after a Corona test and did not receive a test result via the App within 3 days of making the test, it is possible that

• the respective laboratory is not fully linked with the Corona-Warn-App backend.
• the consent field allowing the transmission of the test result to the Corona-Warn-App was not ticked on the submission form (10C/OEGD) sent by your doctor to the laboratory.

Please check whether the laboratory working with your doctor or test center is connected to the Corona-Warn-App and whether the consent field is checked on the form. Only then is it ensured that the procedure used works with the Corona-Warn-App.

Currently, 90% of the existing test capacities in Germany are covered by the complete digital process. We are continuing to work with the laboratories to close the gaps and to connect and upgrade all laboratories for the process. Therefore it can happen that a laboratory gets the order for the test with the correct form, but has to transmit the test result to the tested person in another way.

In this case, please call the responsible medical staff or test center/health authority to get your test result. If you are informed of a positive test result, you can request a TeleTAN from the TAN Hotline (click here to see our phone numbers) to warn your contacts via the Corona-Warn-App. Before you are able to enter the TeleTAN into the app, you have to delete the pending test result from the app. To do this, please tap on

• 'Display Test' -> 'Delete test'

Confirm again that you really want to remove the test result. Now you can enter the requested TeleTAN into the Corona-Warn-App by following these steps:

• 'Next Steps' -> 'Enter TAN'

You can report cases where you waited longer than 3 days for the test result or laboratories that are not connected to the Corona-Warn-App by mail to corona-warn-app.opensource@sap.com. Please provide a scan of the information sheet with the QR code, the date on which you were tested, the number of days you waited for the test result as well as contact information of the doctor or test center. All non-essential personal data should be blacked out. We will then try to resolve connectivity issues and long waiting periods together with the involved parties.

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Red Card? How to go through Corona testing

If the Corona-Warn-App indicates a high infection risk with the red card, please isolate yourself quickly and consult a doctor to get screened if necessary.

For a smooth testing process, to receive the test result and to warn others in case of a positive result, please follow the steps in this overview from the Robert Koch Institute.

See also: Where to get tested?

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Will the device battery drain more quickly with the app running in the background?

The Corona-Warn-App uses the existing Bluetooth technology of the devices: Because the app is built on top of the Exposure Notification Framework from Apple and Google, the energy-efficient BLE (Bluetooth Low Energy) technology is used.

The battery consumption of the Corona-Warn-App is made up of two factors: the consumption of the app itself and the consumption due to the recording of the encounters via the Exposure Notification System. The latter can be optimized by using the currently available operating systems for iOS and Android.

While interpreting your battery consumption, please note that the Corona-Warn-App's displayed percentage of battery usage is relative to the usage of all other apps in the last 24 hours. This means that a frequently and intensively used phone will show a very low percentage of battery consumption for the Corona-Warn-App. On the contrary, if you use your phone mainly to make phone calls and only occasionally stream music or use social media, the percentage of battery usage of the Corona-Warn-App will be relatively high.

Note for Android devices: Bluetooth devices near your device can only be detected if 'Use location' is activated on your phone. For details, see Android: When activating exposure logging or Bluetooth I'm asked to activate my location. Do I have to do this?. This means that other apps on your device could also use your location, which might be the reason for higher power consumption. To avoid this, you should check which apps use your location.

1. Go to your device settings
2. Select 'Security & Location' -> 'Location' -> 'App level permissions'

Here you can deny other apps permission to use your location if you don't think they need it. Since Corona-Warn-App doesn't need this permission, it doesn't appear in the list.

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[Google/Android] A message “Incompatibility warning” on my Start Screen indicates that my device is only partially compatible. What does this mean?

Since version 2.2, the Corona-Warn-App for Android checks whether your device supports all necessary Bluetooth features. If you are seeing this message, the operating system of your device lacks the ability to send random IDs via Bluetooth. However, it is still able to receive random IDs. Your own risk assessment is therefore not affected.

The only limitation caused by this is that you cannot warn contacts discovered via Bluetooth when sharing a positive test result. However, users who were checked in to the same event or the same location, at the same time as you were, will still be warned. The Check-In functionality, the retrieval of PCR and rapid test results as well as the contact journal feature are not affected and can be used normally.

To resolve the problem, please update to the latest version of your device's operating system. If this doesn't help, please contact your device manufacturer.

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Technical explanation

Your device's Bluetooth hardware supports the Bluetooth Low Energy technology which is necessary for distributing random IDs. However, the Bluetooth driver of your operating system is missing a capability called “peripheral mode”. Without this capability, the Corona-Warn-App cannot initiate your device to periodically broadcast its own random IDs via Bluetooth. This can only be fixed by your device manufacturer via an update of your operating system.

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[Google/Android] A message “Incompatibility warning” on my Start Screen indicates that my device is not compatible with Exposure Notifications at all. What does this mean?

Since version 2.2, the Corona-Warn-App for Android checks whether your device supports all necessary Bluetooth features. If you are seeing this message, your device does not support the Bluetooth functionality needed for sending and receiving random IDs. Your risk assessment will therefore only be based on events and locations where you checked in.

The Check-In functionality, the retrieval of PCR and rapid test results as well as the contact journal feature are not affected and can be used normally.

Possible reasons for this message are:

• Your device does not contain the hardware that is required to use Bluetooth Low Energy.
• Your device does not contain the software required to use the Bluetooth Low Energy capabilities of your hardware.
• You are running the app in the Android Emulator.

To resolve the problem, please update to the latest version of your device's operating system. If this doesn't help, please contact your device manufacturer.

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Technical explanation

The Corona-Warn-App needs the Bluetooth Low Energy technology for the distribution of random IDs. However, this technology is not available on your device due to missing hardware or software support. Without this capability, the Corona-Warn-App can neither initiate your device to periodically broadcast its own random IDs via Bluetooth nor receive random IDs from other devices.

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Background Updates

[Apple/iOS]: My risk status hasn't been updated for over a day. An internet connection was available, what's wrong?

First, please ensure that you are running the current version of iOS and the app. The latest version of the Corona-Warn-App is currently 2.3.3. If you are running a lower version, open the App Store to check if an update for Corona-Warn-App is available. Please install it and also restart your device to mitigate the problem. Open Corona-Warn-App once after the restart. You can find additional information in a blog post on LinkedIn (German only).

Make sure that exposure logging is active.

If the latest version still shows the issue, please open the app regularly, at least once a day. We are working on additional updates to solve respective issues.

In addition, please check the following device settings on your phone:

Background App Refresh (in General)

Corona-Warn-App must be able to refresh in the background both via Wi-Fi and cellular data, so you have to allow this in general. Open your device settings, choose 'General' > 'Background App Refresh' and activate 'Wi-Fi & Cellular Data'.

This means that you allow background refreshing in general, but you can decide for each individual app if it really refreshes in the background (see next section).

Important: Mobile/cellular data that are transmitted during the usage of Corona-Warn-App is free of charge and will not be deducted from your data plan!

Background App Refresh for Corona-Warn-App

Check if you have activated background app refresh for Corona-Warn-App as well. Open the device settings, go to 'Corona-Warn', and activate 'Background App Refresh' as well as 'Mobile Data'. As mentioned above: You’re not charged for any data that is transmitted via Corona-Warn-App.

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[Google/Android]: My risk status hasn't been updated for over a day. An internet connection was available, what's wrong?

This problem is usually because some device manufacturers implement their own battery-saving functions instead of accessing the already built-in features provided by Google in its own Android operating system. Apps, such as the Corona-Warn-App, which should cope with tasks in the background, can be prevented from doing so on such devices. This means that a non-functional background update is not due to the app itself, but to specific features of some devices. Below we have put together some measures to mitigate the problem.

First, please ensure that you are running the current version of the app. You should have version 2.3.4 or higher. If you are running a lower version, open the Google Play Store to check if an update for Corona-Warn-App is available. Please install it and also restart your device to mitigate the problem. Open Corona-Warn-App once after the restart.

Make sure that exposure logging is active.

If the latest version still shows the issue, it is probably due to individual power saving modes or battery settings by different manufacturers. These do not fully comply with the Android specifications and often apply aggressive power saving measures. Corona-Warn-App is affected by these power saving settings and therefore often cannot update the risk status in the background for a long time. However, you can change the settings in the Corona-Warn-App:

In order to activate Prioritized Background Activity you need to de-activate optimization of the battery usage:

1. In the Corona-Warn-App (CWA) on the Start Screen choose the three-dot icon in the top right corner, then Settings
2. Choose Prioritized Background Activity (If Prioritized Background Activity is 'On' already, you don't need to take further action here.)
3. Choose 'OPEN DEVICE SETTINGS'
4. You see now the operating system 'Optimize battery usage' / 'Battery optimization' or similar (depends on device model). Choose in the dropdown list 'All' or 'All Apps'
5. Scroll down to Corona-Warn
6. Move the slider to the left (i.e. optimize battery usage off) or tap on the entry and then choose 'Do not optimize' (This procedure depends on the device model.)
7. Cross-check the change in the CWA:
8. In the Corona-Warn-App (CWA) on the Start Screen choose the three-dot icon, then Settings
9. Prioritized Background Activity should be 'On' now.

Samsung offers an additional "Ultra Power Saving Mode" for their devices. This mode often prevents a successful update of the risk status in the background, even if 'Prioritized Background Activity' has been selected. To ensure a proper functionality of the Corona-Warn-App, the Ultra Power Saving Mode should be deactivated. Please refer to the Notes on the Ultra Power Saving Mode on Samsung devices for further instructions.

In the power-saving settings of your phone, you can make sure that there's an exception set for the Corona-Warn-App:

Unfortunately, in some phones, you might not be able to activate the prioritized background activity in the app settings. You can still activate the prioritized background activity: You do so directly in the energy saving settings. of your phone. Set an exception for the Corona-Warn-App. If this still doesn't update the risk status automatically in the background, please create a comment in GitHub issue 933, giving your phone type and the installed versions of the app and of the COVID-19 exposure notifications.

If the latest version still shows the issue, please open the app regularly, at least once a day. We are working on additional updates to solve respective issues.

If all these recommendations did not help as expected, you can make further, smartphone-specific, settings. Software manufacturers, such as Slack, which faced similar problems, have already provided a lot of information to help solve this problem. Please try the tips from the Slack documentation for the Corona-Warn-App and your smartphone: Known issues with Android notifications. If you have a Huawei or Honor phone, please also note these instructions.

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[Google/Android]: Notes on the Ultra Power Saving Mode on Samsung devices

The usage of the Ultra Power Saving Mode on Samsung devices can cause the background updates of the risk status to fail, even if Prioritized Background Activity is activated. This behaviour is likely triggered by the strongly reduced processing power in this mode, which results in an abort of the background updating process. The Ultra Power Saving Mode should therefore be deactivated in the settings:

1. 'Settings' -> 'System' -> 'Power saving'
2. Select 'Ultra Power Saving Mode'.
3. Open the menu in the upper right and select 'Turn off Ultra power saving mode'.

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Notifications

[Apple/iOS]: Error 13

The Error 13 is thrown by Apple's Exposure Notification Framework, which is used by the Corona-Warn-App. It will appear if more than 6 exposure checks happened in the last 24 hours. Apple does not allow more than 6 exposure checks within 24 hours. The error will disappear after 24 hours at the latest. You don't have to do anything.

Please do not remove and reinstall the Corona-Warn-App, because the error is caused by the underlying Apple Exposure Notification Framework which is independent from the app. Therefore, it will persist, even after reinstallation.

If the Error doesn't disappear after 24h, please open an issue on GitHub.

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[Google/Android]: Error after resetting the app: Limit already reached

If you encounter the following error message after resetting the app, please wait until the next day before you open the app again.

'Limit already reached'

'No more exposure checks possible today, as you have reached the maximum number of checks per day defined by your operating system. Please check your risk status again tomorrow.'

The error should have disappeared by then and your risk status should be displayed correctly.

This error can occur if you reset the app between 20:00 and 00:00 and your device was constantly connected to Wi-Fi for the whole day. The Corona-Warn-App has a daily limit of 6 periodic checks. In this case, resetting the app triggers an unscheduled risk check that can exceed the daily limit. The functionality of the app is not affected by the failed check.

If the error message is still present the next day, you can report this via a comment in GitHub Issue 1459.

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My exposure log shows checks for less than 14 days

Your phone settings display the exposure checks for the last 14 days:

• iOS: 'Settings' -> 'Exposure Notifications' -> 'Exposure Logging Status' -> 'Exposure Checks'
• Android: 'Settings' -> 'Google' -> 'COVID-19 Exposure Notifications' -> three-dot icon -> 'Exposure Checks'

When the app was running constantly during the last two weeks, you should see at least one check every day for all of the past 14 days.

Please note: The log is just the history. After every background update, the exposures of the last 14 days are checked and the risk status calculated. The important thing is that the exposure log shows at least one check for the last 24 hours.

It might be that entries are displayed for less than 14 days, although exposure was checked correctly. There are several reasons:

1. The log has a fixed limit of 100 entries on iOS devices. On Android devices the limit is 300 entries. If there are more entries, only the latest are kept.
2. If you use the app only recently (let's say for 5 days), only checks that were made after setting up the app are displayed - at least one for every day that the Corona-Warn-App was running constantly.

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Message: „Something went wrong. Due to a technical problem your app has been reset“

Starting with Corona-Warn-App version 1.5.0 or higher, it may happen that after opening the app you get the notification „Something went wrong. Due to a technical problem your app was reset“.

What happened?

An error occurred while accessing the database, which means that the encrypted data can no longer be accessed. The Corona-Warn-App has detected this error and automatically reset the databases, so that access is now working again and the Corona-Warn-App can still inform you about your risk status. More technical details about this problem can be found below.

What should you consider?

Resetting the databases has no effect on the risk determination and therefore not on your risk status. All recorded encounters with other people using the app will be preserved. You will still be notified about risk encounters and can warn others if you test positive for COVID-19.

However, if you have scanned a PCR-Test QR code for electronic notification of a COVID-19 test and the test result has not yet been sent to you in the App, resetting the databases will cause the test to lose its registration for electronic transmission. For data protection reasons, the PCR-Test QR code can unfortunately not be read in again. Please contact your physician or the laboratory to obtain your test result.

Resetting the data also means that the information on how long your app has been active is lost (the number of active days is set to 0). Entries may have also been removed from the history of encounter records, which you can access via your Google Account settings. (see here and here) However, this has no effect on the risk determination and your risk status. After 24 hours at the latest, your risk status should be displayed again and new entries should appear in the history of the encounter records.

Technical background

The Corona-Warn-App was developed with the highest standards of data protection. For this purpose, data is stored in encrypted form and the program code of the app is made available for public review (open source approach). In order to realize data encryption for an app, developers like to fall back on program modules that have already been tried and tested in the past and are also made available as open source by other developers. This way, transparency for all components of the Corona-Warn-App can be guaranteed. Only recently it became known that an encryption module, which is also used by the Corona-Warn-App, works incorrectly if the memory for keys or passwords integrated in the Android operating system does not react reliably. This error leads to the fact that an encrypted database can no longer be opened. This in turn causes some users to see the message „Cause: 9002 Something went wrong (sqlite)“ or the app can no longer be opened. Of course, the Corona-Warn-App is thoroughly tested before each release of an update. However, this error never occurred during the tests and it is still difficult to reproduce.

All parties involved work together to resolve the error as quickly as possible.

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I suddenly have problems with other apps and devices that use Bluetooth. What can I do?

Some users report that their device behaves differently since they installed Corona-Warn-App. Example: Sometimes the communication between their phone and Bluetooth devices via other apps is interrupted. This affects, for example, smart watches or Bluetooth earphones. We are investigating these issues, but this is likely a problem with the basic operating system functions, over which we have no control.

Please try the following:

• Restart your device.
• Unpair the other Bluetooth-connected devices and recouple them.

If the above does not help, contact your device manufacturer:

• Apple/iOS: Apple Support
• Android phones: Get help from your device’s manufacturer

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Availability

What are the minimum operating system requirements for my phone?

UPDATE February 10, 2021

iOS - Minimum operating system requirements

The minimum operating system level for iPhone 5s, iPhone 6 and iPhone 6 Plus devices is iOS 12.5. For iPhone SE (1st generation), iPhone 6s, iPhone 6s Plus and newer iOS devices the minimum is iOS 13.7. These versions of the iOS operating system include the necessary v2 version of the Apple Exposure Notification Framework.

See also [Apple/iOS]: Why is iOS 13.7 a minimum requirement? and the blog articles Telekom and SAP to make Corona-Warn-App available for iOS 12.5. and Corona-Warn-App version 1.12 comes with two new features

Android - Minimum operating system requirements

The minimum operating system level for all Android devices is version 6 of Android. In addition, the device must have Google Play services installed, with a minimum version 1.5 of the Google Exposure Notification System (ENS). See [Google/Android]: Which version of the COVID-19 Exposure Notification System is currently installed? for instructions about how to find out which version of ENS is installed.

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Prior FAQ Entry

Apple/iOS: Corona-Warn-App runs on the iPhone 6s or higher. Although the Exposure Notification API was introduced with iOS 13.5, your operating system needs to be iOS 12.5 or higher, since Corona-Warn-App uses version 2 of the Exposure Notification Framework which was introduced with iOS 12.5.

Google/Android: Corona-Warn-App runs on phones with Android 6 or higher. Google Play services install the Exposure Notification API automatically.

For other operating system-related questions, please contact Apple or Google.

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[Apple/iOS]: Why is iOS 13.7 or iOS 12.5, respectively, a minimum requirement?

UPDATE February 10, 2021
The Corona-Warn-App version 1.12 also supports the older iPhone models iPhone 5s, iPhone 6, and iPhone 6 Plus. On these devices, the iOS operating system must be upgraded to at least iOS 12.5.

Apple provides the operating system iOS 13.7 and higher versions for the iPhone SE (1st generation), iPhone 6s, and newer models.

As of February 5, 2021, only the Corona-Warn-App (CWA) versions 1.5.3 and later are supported. For this reason, users with older versions will receive a notification to update their app accordingly. iOS users who have previously used iOS 13.5 and CWA version 1.3, for example, must now update the iOS operating system to at least iOS 13.7 in order to continue using the CWA. Only then can the technically correct operation of the app be ensured.

• Please update your iOS version first. Older smartphones, such as the iPhone SE, 6S or 6S Plus, also support the latest iOS operating system. This allows you to upgrade your iPhone to at least iOS 13.7. For security reasons, however, you should keep your iPhone up-to-date (currently iOS 14.4), as Apple also regularly fixes minor security vulnerabilities with the updates. You can do this on your iPhone under Settings - General - Software Update.
• Subsequently, please update the Corona-Warn-App. The Corona-Warn-App must also be installed at least in version 1.5.3. The version 1.12.1 is already available.

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More details about the system requirements can be found in this FAQ entry.

See also the blog articles Telecom and SAP will make the Corona-Warn-App available for iOS 12.5. and Corona-Warn-App version 1.12 comes with two new features

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Apple introduced the required Exposure Notification API with iOS 13.5, see About iOS 13 Updates. With version 1.9 of the Corona-Warn-App (and the use of version 2 of the Exposure Notification Framework), iOS 12.5 is now required, as version 2 of Exposure Notification API has been introduced with this version. You can find the supported devices here: Supported iPhone Models. Unfortunately, Apple no longer supports devices that are older than 4-5 years. We as app developers, unfortunately, cannot influence this.

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[Apple/iOS]: I am testing a beta version of iOS. Why is the Corona-Warn-App not yet supported?

We do not officially support beta versions of the respective operating systems. These are still in development and not intended for productive operation.

However, if you as a participant in the Apple beta software programme would like to point out potential errors or incompatibilities at an early stage, we are happy to receive your feedback on Github.

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[Google/Android]: Can I also use the app on a rooted device?

No, the app is not supported on rooted devices.

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[Google/Android]: Why are Android 6 and Google Play Services minimum requirements?

Google delivers the required Exposure Notification API for contact tracing apps with Google Play Services. The API is supported starting with Android API level 23. This version is available starting with Android version 6.0, see Codenames, Tags, and Build Numbers. This was decided solely by Google. In addition, older devices sometimes don’t support Bluetooth Low Energy. We as app developers, unfortunately, cannot influence this.

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In which languages is the Corona-Warn-App available?

The app is currently available in the following languages:

• German
• English
• Turkish (as of version 1.1.1)
• Bulgarian (as of version 1.2.0)
• Polish (as of version 1.2.0)
• Romanian (as of version 1.2.0)

The technical hotline (0800 7540001) answers in Turkish, English and German. More languages are to come. We'll keep you up to date.

The language of the app is derived from the language that is configured in the smartphone's language settings. To display the app in German, for example, change the language settings to German.

Please note that many countries release their own Corona tracking apps. Because the German Corona-Warn-App is also available in the app stores and play stores of these countries, the Corona tracking apps could be mixed up. Therefore, make sure that you download the app for your country.

See also How to reach us from abroad.

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In which international app stores is the app available?

After a detailed examination of the situation it was determined that for legal reasons any publication of the Corona-Warn-App in App Stores outside of Germany is currently only possible after a case-by-case assessment. Legal consultations have shown that in the case of publication in international App Stores, the law of the respective country must be considered and applied to the Corona-Warn-App. This applies in particular to data protection, any necessary claims for information by local authorities and other contractual and consumer protection regulations.

The Robert Koch Institute as publisher of the app will trigger this check for the respective countries and release the app after successful legal examination. The RKI currently released the app for the following European countries:

• Austria
• Belgium
• Bulgaria
• Croatia
• Cyprus
• Czech Republic
• Denmark
• Finland
• France
• Germany
• Greece
• Hungary
• Iceland
• Ireland
• Italy
• Latvia
• Lithuania
• Luxembourg
• Malta
• Netherlands
• Norway
• Poland
• Portugal
• Romania
• Sweden
• Slovakia
• Slovenia
• Spain
• Switzerland
• United Kingdom

More countries are currently being checked and will be released in the App Stores step by step. The Robert Koch Institute asks for your understanding that it cannot provide any information on specific countries and the status of their release during the ongoing review process.

Please note that many countries release their own Corona tracking apps. Because the German Corona-Warn-App is also available in the app stores and play stores of these countries, the Corona tracking apps could be mixed up. Therefore, make sure that you download the app for your country.

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In which countries can the Corona-Warn-App be used?

Together with the European Commission, an infrastructure for secure information exchange has been developed, known as the "Interoperability Gateway". This gateway enables the Corona-Warn-App to operate across national borders and to receive potential warning messages abroad. Detailed information about the Gateway is available from the European Commission in Coronavirus: EU interoperability gateway for contact tracing and warning apps – Questions and Answers. In order to also enable warnings between users of the Swiss coronavirus app and the Corona-Warn-App, the RKI also operates another exchange server together with Switzerland (Federal Office of Public Health of the Swiss Confederation).

To view more information in the app, tap

1. 'EXPOSURE LOGGING ACTIVE/STOPPED'
2. Then tap 'Transnational Exposure Logging'.
3. Scroll down to the list of countries.

Below is a list of currently participating countries and details of the responsible health authorities:

(Status: 12.05.2021)

Country	Data Controller	Contact Details
Austria (from 04.02.2021)	Austrian Red Cross	General ministry and blood donation centre for Vienna Lower Austria and Burgenland Wiedner Hauptstrasse 32 1040 Vienna Austria E-Mail: service@roteskreuz.at Phone: +43 1 58900 955
Belgium (from 06.01.2021)	Sciensano	Sciensano Juliette Wytsmanstraat 14 BE-1050 Ixelles/Elsene Belgium E-Mail: coronalert@sciensano.be or dpo@sciensano.be Phone: +32 479 317 455
Croatia (from 16.11.2020)	AZOP Croatian Personal Data Protection Agency	AZOP Croatian Personal Data Protection Agency Selska cesta 136 10000 Zagreb Croatia E-Mail: azop@azop.hr Phone: + 385 14609000
Cyprus (from 15.12.2020)	Ministry of Health (MoH)	Ministry of Health (MoH) 1 Prodromou & 17 Chilonos Street CY-1449 Nicosia Cyprus E-Mail: cyjointcontroller@mphs.moh.gov.cy E-Mail (DPO): MPHS_DPO@mphs.moh.gov.cy Phone (DPO): +357 22605603
Czech Republic (from 22.03.2021)	Ministry of Health of the Czech Republic	Ministry of Health of the Czech Republic Palackého náměstí 4 128 01 Praha 2 Czech Republic E-Mail: oia@mzcr.cz Phone: +420 224 972 457
Denmark (from 06.11.2020)	Styrelsen for Patientsikkerhed (Danish Patient Safety Authority)	Styrelsen for Patientsikkerhed Islands Brygge 67 2300 København S Denmark E-Mail: stps@stps.dk Phone: +45 72286600
Finland (from 07.01.2021)	National Institute for Health and Welfare (THL)	National Institute for Health and Welfare (THL) PO Box 30 FI-00271 Helsinki Finland E-Mail: tietosuoja@thl.fi Phone: +358 29 524 6000
Germany (from 17.10.2020)	Robert Koch Institute	Robert Koch Institute Nordufer 20 13353 Berlin Germany E-Mail: CoronaWarnApp@rki.de Phone: +49 30187540
Ireland (from 19.10.2020)	Health Service Executive	Dr Steevens’ Hospital Steevens Lane Dublin 8 Irland E-Mail: cio@hse.ie Phone: +353 87 688 3565
Italy (from 19.10.2020)	Ministry of Health	Ministry of Health Viale Giorgio Ribotta 5 00144 Rome Italy E-Mail: segretariato.generale@sanita.it Phone: +39 65994694546
Latvia (from 06.11.2020)	Slimību profilakses un kontroles centrs	Slimību profilakses un kontroles centrs (SPKC) Duntes iela 22, k-5 Rīga, LV 1005 Latvia E-Mail: pasts@spkc.gov.lv Phone: +371 675015 90 or -91
Lithuania (from 12.05.2021)	Ministry of Health of the Republic of Lithuania	Ministry of Health of the Republic of Lithuania Vilniaus St. 33 T-01506 Vilnius Lithuania E-Mail (DPO): duomenu.apsauga@sam.lt E-Mail (Data subject rights): duomenu.apsauga@nvsc.lt
Malta (from 15.04.2021)	Department for Health Regulation	Department for Health Regulation Office of the Superintendent of Public Health St. Luke’s Hospital, Outpatients Block Level 1 St. Luke’s Square Pietà PTA 1010 Malta E-Mail: sph.health@gov.mt E-Mail (DPO): dpo-osph@gov.mt Phone: +356 2595 3302 / +356 2595 3303
Netherlands (from 30.11.2020)	Minister of Health, Welfare and Sports	Minister of Health, Welfare and Sports Postbus 16114 2500 BC The Hague Netherlands E-Mail: CIBG-eHealth-EU@minvws.nl or FG-VWS@minvws.nl Phone: +31 703405487
Norway (from 15.02.2021)	Folkehelseinstituttet/Norwegian Institute of Public Health	Folkehelseinstituttet/Norwegian Institute of Public Health Postboks 222 Skøyen 0213 Oslo Norway E-Mail: folkehelseinstituttet@fhi.no Phone: +47 21 07 70 00
Poland (from 23.11.2020)	Główny Inspektor Sanitarny (Chief Sanitary Inspector)	Chief Sanitary Inspector ul. Targowa 65 203–729 Warsaw Poland E-Mail: protego@mc.gov.pl Phone: +48 223453300
Slovenia (from 15.02.2021)	Ministry of Public Administration (MJU) and Ministry of Public Administration (MJU)	Ministry of Public Administration (MJU) Tržaška cesta 21 1000 Ljubljana Slovenia E-Mail: gp.mju@gov.si E-Mail (DPO): dpo.mju@gov.si Phone: tbn and National Institute of Public Health (HIJZ) Trubarjeva 2, 1000 Ljubljana Slovenia E-Mail: info@nijz.si E-Mail (DPO): vop@nijz.si Phone: tbn
Spain (from 06.11.2020)	Ministerio de Asuntos Economicos y Transformacion Digital	Ministerio de Asuntos Economicos y Transformacion Digital P. de la Castellana, 162 28071 Madrid Spain E-Mail: soporte.radarcovid@economia.gob.es Phone: +34 91 258 28 52
Switzerland (from 24.03.2021)	Bundesamt für Gesundheit BAG	Bundesamt für Gesundheit BAG 3003 Bern Switzerland E-Mail: rech@bag.admin.ch Phone: +41 58 462 69 98

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Why are there different age restrictions to use the app on Android and Apple devices?

The app is aimed at people who are at least 16 years old. Of course, custodians are free to allow children and young people under the age of 16 to use the app.

However, the age restrictions applicable in the Apple App Store and the Google Play Store are determined exclusively by the respective companies on the basis of various criteria. Therefore, the age limit in the Apple App Store is '12+' and in the PlayStore is '0+'.

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[Google/Android]: The app isn’t available as an APK, neither on GitHub nor on F-Droid etc. Will you also deliver the app as an APK?

Delivery via alternative distribution channels (download via APK, F-Droid etc.) is not planned for various reasons.

On the one hand, the Robert Koch Institute, which is legally and content-wise responsible for its distribution, is responsible for the delivery of the app. At the moment, the focus is only on delivery via the respective App Stores. Furthermore, the app only works with Google Play Services. With a distribution via the Play Store it can be assumed that Google Play Services are installed. We cannot make these assumptions for other distribution channels at the moment.

The distribution of the existing app on other channels is currently published as a request on corona-warn-app/cwa-wishlist#57. The discussion about alternative distribution platforms such as F-Droid can be found at corona-warn-app/cwa-documentation#5.

Furthermore, there is an initiative in the developer community to make the Corona-Warn-App executable independently of Google Play Services via appropriate extensions. Details can be found in the issue corona-warn-app/cwa-app-android#75.

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Will the app also be available on tablets, smart watches, and other wearables?

We don’t plan to implement the app for tablets, smart watches, and other wearables. Our focus is on smart phones, for example because of the availability of the required APIs. If we change this approach, we will of course communicate this widely.

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Will the app be made available on platforms other than Apple App Store and Google Play Store?

It's not foreseeable at the moment if and when the app will be available in other app stores except Google or Apple. The app will use the Apple and Google Exposure Notification APIs. The community is invited to contribute and use the app for other APIs.

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A new version of the Corona-Warn-App is supposed to be available, but I have not received the update yet. What do I do?

Updates for the Corona-Warn-App are distributed using a so-called "staged rollout" over a timespan of 48 hours. This means that, instead of distributing the update immediately to every user, the update is gradually made available to a larger percentage of users over time. By using a staged rollout, critical bugs and crashes can be detected early and be addressed by the development team before they affect a large amount of users.

The order in which users receive the update is randomly determined for every release by the app store vendors. Therefore, you might receive the update up to two days after the official release date. The Corona-Warn-App development team has no influence on the order in which users receive the update.

Please note: On iOS, it is possible to manually trigger the update by visiting the App Store page of the Corona-Warn-App. This option does not exist on Android.

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Where can I get the app?

You can download the Corona-Warn-App from the Apple App Store or Google Play Store.

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Use

What to do with several PCR-Test QR codes?

At the moment, many families are tested at the airport after returning from their holidays. For each family member that is being tested, they get a leaflet that displays a PCR-Test QR code.

1. Read through the leaflet carefully, to make sure if the QR code really is to be scanned with the Corona-Warn-App, or if it is meant for another test infrastructure.
2. Only if you made sure that the QR code is to be scanned with the Corona-Warn-App and not for another system, proceed in the Corona-Warn-App.
3. You can scan each PCR-Test QR code only once with the Corona-Warn-App. After scanning, the QR code expires. This prevents misusing the QR code.
4. If you received a PCR-Test QR code for your own test, scan it with the Corona-Warn-App and wait until the result is retrieved. This can take from a couple of hours up to a few days. Open the Corona-Warn-App regularly to check if the test result is already available.
5. If you received additional QR codes for tests of your family members, for example, your kids who do not have their own phones, DO NOT scan their QR codes with your phone. Only use your QR code with your personal test and your personal smartphone. In any case, your family will be notified about their test results independently, usually by calling them.
6. If your QR code doesn't work and you received a positive test result: Call the TAN hotline (0800 7540002) to receive a TeleTAN. You can then enter the TeleTAN in your Corona-Warn-App so that the persons you encountered in the past days can be informed over the Corona-Warn-App. Please pay attention to the recommendations the Corona-Warn-App displays.

See also How to reach us from abroad.

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What do the exposure check logs show?

The exposure check logs show how many keys that report a positive test result are downloaded from the server, and how many of them are matching the keys that your phone has collected. For info about the app flow, see How do you get information about a risk of infection? for details.

Exposure checks

This value does not reflect the number of encounters. Please tap one level further: This is where the checks of up to 15 days are logged (today plus the last 14 days). Selecting an entry leads to a detailed view with the corresponding time stamps and the number of matched keys.

Provided Key Count (Apple) | Number of keys (Android)

This is the number of keys related to a positive test result, so called diagnosis keys, that your phone downloaded from the server.

Matched Key Count (Apple) | Number of matches (Android)

This is the number of keys that your phone collected for which there is a matching diagnosis key. If the number is not 0, then you had an exposure. If your risk status stays green, that is, 'Low Risk', find more information at An encounter has been reported, but the risk status stays green.

Timestamp

Date and time at which the check happened. This is independent of the timestamp of potential exposures since every key stored in the downloaded files, a separate validity timestamp is stored.

Data Source

Identifies the app that initiated the check. If you, for example, also installed Immuni or SwissCovid, their app identifiers could be noted there instead of 'Corona-Warn'.

Hash

Checksum of the file containing the downloaded diagnosis keys. As long as the file content (diagnosis keys) does not change, this checksum will not change throughout the relevant time frame of 2 weeks.

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Will exposure logging still work when I close the app?

Yes. As long as you have activated exposure logging in the app and Bluetooth (and Location Services on Android) is on, encounters are logged in the background by the Exposure Notification system integrated in iOS/Android. The app itself doesn't have to be open for this. You can minimize it or use 'swipe-to-quit' to close it.

To be on the safe side, open the app once a day. You'll find more info at This is how the app works best.

For the risk status to be updated automatically, make sure that background updates are active. For all the info, see these FAQ:

• [Apple/iOS]: My risk status hasn't been updated for over a day. An internet connection was available, what's wrong?
• [Google/Android]: My risk status hasn't been updated for over a day. An internet connection was available, what's wrong?

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How are the days since the last encounter counted?

The number of days is counted as normal - '1 day since the last encounter' means 'yesterday', '2' the day before yesterday. The details of the technical implementation are explained here by Apple.

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[Apple/iOS]: What happens if I switch off Bluetooth?

Then, encounters with other devices that have the Corona-Warn-App running are not logged, because the devices will not exchange random IDs, and the app is not able to perform risk checks. Therefore, make sure to have Bluetooth active at all times to receive warnings about a high risk of exposure to COVID-19 as soon as possible.

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[Google/Android]: What happens if I switch off Bluetooth and the Location Services?

Then, encounters with other devices that have the Corona-Warn-App running are not logged, because the devices will not exchange random IDs. For devices running Android 10 or below, the location services have to be active, but the Corona-Warn-App does not use the location information. You can deny other apps to use your location, if you want. See this FAQ entry, for more information:

[Google/Android]: When activating exposure logging or Bluetooth I'm asked to activate my location. Do I have to do this?

If your device is using Android 11 or above, Location Services can be switched off without affecting the functionality of the app.

Make sure to have Bluetooth (and for Android 10 and below, the Location Services) active whenever you meet someone, e.g. when you have guests or are going outside.

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[Apple/iOS]: Will exposure logging still work if I turn off Bluetooth in my Control Center while keeping it activated in the system settings?

Yes. The option in Control Center (see Use Bluetooth and Wi-Fi in Control Center) only disconnects your phone temporarily from any Bluetooth accessories that are currently connected. Bluetooth itself remains activated in the system settings.

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Will the collected random IDs be included when I backup data on my phone?

No, they are not included in the backup. This also means that you can't restore the collected random IDs on the same or a different device.

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What do I have to consider when switching to a new device?

A backup of the old random IDs is unfortunately not possible, because the Exposure Notification Framework of Apple/Google does not allow the export of this data. To still be informed about possible risk encounters, we recommend that you keep a close view of the risk status on the old device for at least 14 days after you install the Corona-Warn-App on the new device. Please note the following instructions:

• Your old device must be able to perform regular checks for possible encounters. Therefore, leave the device permanently turned on and permanently connected to the Internet.
• Keep the old device in a stationary location, e.g., in a specific place in your apartment. If possible, place the device where you can hear or see it so that you are alerted early by a notification of the app.
• Actively access the Corona-Warn-App on the old device at least once a day and check your risk status there.

If you are tested for COVID-19 during these 14 days, enter the PCR-Test QR code on your new device. If the test result is positive, you should share the test result on both devices. For sharing a test result on multiple devices, please note the FAQ entry How do I share a positive test result on multiple devices?.

After 14 days, your old device will no longer contain any relevant entries for risk assessment. You don't need to pay any further attention to the risk status on this device and can remove the Corona-Warn-App there.

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Are the exposure logs/random IDs removed from my phone when I uninstall the app?

Uninstalling the app should always be a last resort for solving one of the known or other issues with the app.

Since the app cannot delete the exposure logs by itself, whether they are cleared or not is a decision of the Exposure Notification System.

In the current version, uninstalling the app on iOS devices leaves the exposure log intact without any guarantees for the duration of storage.

On Android devices, the current implementation deletes the 'database and keys' from the device when uninstalling the app. Hence, you should expect that the collected random IDs are deleted when the app is uninstalled. Random IDs are also deleted if the Android operating system storage maintenance 'Clear data' function is used on the App 'Corona-Warn'.

The way un-installation is handled can change without notice and without changes to the Corona-Warn-App itself. Therefore, only uninstall the app as a last resort to resolve an error and only when instructed to, e.g., by the technical hotline or developers on GitHub.

We recommend that before you re-install the app, you try resetting the app first as this will not delete the random IDs:

• On iOS devices, choose 'Settings' -> 'Reset App' on the home screen.
• On Android devices, choose the three dots at the top right corner of the home screen and select 'Settings' -> 'Reset App'.

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How do I get informed about a risk of infection?

This is how the app works:

1. All devices that have the Corona-Warn-App installed send and receive random IDs, which are saved locally on your device. A Bluetooth connection between two devices is only necessary for sending and receiving random IDs.
2. If you are diagnosed with COVID-19, you can upload the random IDs your device sent via Bluetooth to the Corona-Warn-App backend. At regular intervals, all devices with the app download these random IDs from the backend and check locally if they have received a matching key via Bluetooth. For uploading and downloading the random IDs, your phone must be able to access the Internet, for example, using WiFi or mobile data.
3. If there is a match between a key downloaded from the server and a key saved locally on your device, this means you were exposed to a person who has been diagnosed with COVID-19.
4. Based on the matched encounters, the app calculates your personal risk score that determines whether you get displayed a "low risk" (green) or "high risk" (red) card in the app. You can find out more about the risk calculation in the FAQ entry By which criteria are encounters evaluated and how do the recommendations for action differ?

The Solution Architecture Document describes the technical process in detail.

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When do I receive my test result in the app?

Currently, analyzing the test in the laboratory and reporting the test result to the Corona-Warn-App servers takes 22-28 hours on average. However, the waiting time can be up to 48 hours depending on the commissioned laboratory. In most cases, you will receive your result the next day or the day after. If your result is not available in the app after 3 days, please follow the advice in FAQ entry: I have scanned a PCR-Test QR code, but the test result could not be retrieved for days.

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How do I enter a negative test result?

Thank you that you want to help. Corona-Warn-App is all about informing your contacts when you have tested positive for COVID-19. That's why you won't find an option for entering a negative test result.

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How do I share a positive test result on multiple devices?

If you have more than one smartphone (e.g. work and private), we recommend that you install the CWA on your private device first. Also, when scanning PCR-Test QR codes and sharing a positive result, we recommend that you first use your private device. If you additionally want to share a positive result via your company device or any other additional smartphone, this can be done via a so-called TeleTAN. By contacting the TAN hotline 0800 7540002 with a positive test result, you will receive a 10-digit TAN with which the test result can also be registered in the app. Please note: The TAN number is only valid for one hour.

See also How to reach us from abroad.

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Can I enter positive test results from other countries?

If you are in another EU country or in one of these countries and have made a molecular biological test (PCR test) which is positive, you can upload it to the Corona-Warn-App. To do so, it is necessary to verify your identity by calling the TAN hotline 0800 7540002. You will receive a 10-digit TAN with which the test result can be registered in the app. Attention: The TAN is only valid for one hour!

See also How to reach us from abroad.

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Can the Corona-Warn-App put me on sick leave, instead of my doctor?

No, it can't. The PCR-Test and Rapid-Test QR codes are designed to verify positive or negative test results. When you are informed by the Corona-Warn-App, this does not replace the report from the doctor or the laboratory that provided the test. Only they can provide you with a document that you show your employer.

The reason is, that the Corona-Warn-App follows the decentralized approach, meaning that the notifications of the Corona-Warn-App do not contain personal data such as name or date of birth. These identifiers are required for releasing you from quarantine, though.

In addition to the displayed test results in the Corona-Warn-App, you'll get written notification from the laboratory, the test center, or your doctor.

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How do I tell the app that I recovered from COVID-19?

Since version 1.13, you have the option to reactivate the app after recovering from a SARS-CoV-2 infection and to restart the risk assessment after sharing your own random IDs. This means that you can now decide if and when to turn risk assessment back on once having shared your encrypted random IDs after a positive test result, thus warning others. Previously, this was only possible via a reset of the app.

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I'm deaf or hard of hearing, so making phone calls is a problem for me. What do I have to keep in mind when I'm using the app?

First of all: The app fulfills accessibility requirements (see scoping document) and supports all accessibility features of your phone's operating system.

In general, you're not required to make phone calls in connection with the Corona-Warn-App. In case of a positive test result, you will get the result via a PCR-Test QR code, which you can scan into the app. If the testing facility doesn't support QR codes or if you don't want to use them, you receive a TAN. Only if you have received neither a QR code nor a TAN, would you have to call the TAN hotline, which you might not be able to do without outside help.

If you can't make phone calls because you're hard of hearing, you should mention this during the test, because this will affect the whole communication process. You will then receive the TAN, if necessary, in writing.

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How often is the risk status updated?

The Corona-Warn-App updates the risk status at least every 24 hours. The actual time can lag behind for a few hours from the time of the day before.

Since CWA version 1.7, exposure checks are run up to 6 times per day when a Wi-Fi connection is present. The repeated daily check is performed automatically. While using mobile data, the check is only performed once every 24 hours due to the zero rating commitment of the network providers.

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When I'm not connected to a Wi-Fi network, will I be charged for any mobile data transmitted via the app?

The German network operators have committed themselves to a so-called zero rating. This means that the mobile data volume for the use of the Corona-Warn-App is provided free of charge both in Germany and within the EU. Mobile data that is transmitted via the Corona-Warn-App when diagnosis keys are uploaded or when the server notifies you in case of exposure is free of charge and will not be deducted from your data plan.

The zero rating applies to all SIM cards that are distributed by German network providers. It does not matter whether they were purchased directly from the mobile phone provider or from a partner company (e.g. discounters).

We are not able to provide any statement for foreign providers of SIM cards. The decision whether the necessary data volumes are provided free of charge or not, is solely up to the respective provider.

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[Google/Android]: Which version of the COVID-19 Exposure Notifications System is currently installed?

Google publishes mobile device support for the COVID-19 Exposure Notifications System using the Google Play Store update services, as a module of Google Play services, that is, independently of the Android operating system. Version 1.5 of the Exposure Notifications System (ENS), which was released in July 2020, introduced the ExposureWindow mode (also referred to as v2 mode) in addition to the previous v1 mode. The Exposure Notifications System Version 1.5 or higher is required for the Corona-Warn-App Version 1.9 and all higher versions of the app.

To check which ENS version is installed on your phone:

1. Open the Corona-Warn-App menu on the Start Screen by choosing the 3-dot icon on the top right, then tap 'App Information'.
2. Scroll down to the bottom of the page to the number next to 'ENF Version', which is displayed in the following format in Version 1.5 of the Exposure Notifications System and higher:
   • VVYYWWxxxxx, where VV is the version of the COVID-19 Exposure Notifications System, YY is the year and WW is the week number (e.g.'18210214000' signifies Version 1.8).

Alternatively, open your device Settings, then select 'Google > COVID-19 Exposure Notifications' where you can find the Version displayed at the bottom of the page.

Google provides general and release information about the COVID-19 Exposure Notifications, see:

• Use the COVID-19 Exposure Notifications System on your Android phone
• Exposure Notifications API
• Exposure Notifications release notes
• Exposure Notifications document change log
• Snapshot of code from Google Play services' Exposure Notifications module

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Risk Assessment

Dissimilar indication of risk status

Why do differences in infection risk status appear in different CWA apps, even for close-by smartphones?

Varying infection risk ratings are caused by several reasons. However, they do not affect the effectiveness of the Corona-Warn-App (CWA).

The assessment of a possible infection risk depends on the recorded contact duration and the determined distance to the smartphone of a CWA user who reported the positive test result. The distance determination is thereby also affected by the orientation of the two smartphone antennas with respect to each other. Therefore, this aspect of the risk assessment depends largely on physical location of the involved smartphones and on spatial conditions.

Moreover, many processes on the smartphones are background processes; they will start at different times depending on the scheduling of the operating system. Examples of those processes are the risk calculation process, downloading of positive keys that takes place several times a day when WiFi access is available, and as well the scanning for other smartphones with an active CWA running.

Furthermore, the CWA supports different Exposure Notification Framework (ENF) versions, depending on the version number of the app and the used operating system. This framework is implemented and provided by Google and Apple. Since not every smartphone supports the latest ENF release, also different ENF versions may lead to different risk calculations.

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Virus variants ("Mutations")

Update
To date, the risk assessment was improved and adapted on the 23.02.2021, on the 19.03.2021 and on the 16.04.2021. More information can be found in our blog:

• 23.02.2021 - Corona-Warn-App’s risk calculation further adjusted after detailed tests
• 19.03.2021 - Corona-Warn-App's risk calculation further improved
• 16.04.2021 - Project Team further improves Corona-Warn-App's risk calculation in response to current coronavirus situation

We will continue to monitor the risk assessment regarding the virus and improve it if necessary.

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Since the very beginning of the pandemic, new virus variants have been discovered worldwide and examined and evaluated by experts with regard to infectiousness and health consequences. The Corona-Warn-App developers are in close contact with the authorities. If the risk of infection changes based on new findings, we certainly will adjust the risk calculation of the app.

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Previously, my app would display one or more low risk encounters - since the update to version 1.9 of the Corona-Warn-App, these have disappeared or rather the number decreased.

With the introduction of Corona-Warn-App version 1.9, a new version of the Exposure Notification Framework (ENF) from Apple/Google is used, version 2.0 (also known as ExposureWindow mode by Google). The data from this interface is used as the basis for calculating the individual risk.

Up to version 1.7.1, the numbers of encounters displayed in the app were not filtered. Encounters with very short contact durations (a few seconds were sufficient) were also counted and displayed in the app. However, due to the stored criteria for the risk calculation, these were only displayed as low-risk encounters.

With the interface's new version, it is now possible to control more precisely which encounters are considered for the risk calculation. Encounters with a very short contact duration or very low signal strength are filtered, since they pose a non-significant risk of exposure. These encounters will still show up in the operating system's contact log, but do not count towards the overall risk score in the app.

To be considered as an encounter, the following conditions must be met within a 30-minute time window:

• The signal attenuation must have been below 79dB for at least 5 minutes.
• The transmission risk level must be at least III (3). It is determined when sharing the diagnosis codes per day according to defined criteria such as symptom status and/or symptom onset.

If these criteria are not met, an encounter is not counted within the app. It is a 'non-risk encounter'.

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How does the app calculate the risk (version >=1.9)?

With the introduction of Corona-Warn-App version 1.9, a new version of the Exposure Notification Framework (ENF) from Apple/Google is used, version 2.0 (also known as ExposureWindow mode by Google). The data from this interface is used as the basis for calculating the individual risk.

While the interface's first version 1.0 used average attenuation values for all encounters with another device during the course of the day, the new version 2.0 now considers 30-minute time windows.

Each of these windows must meet certain criteria to be considered:

• The signal attenuation must have been below 79dB for at least 5 minutes within the 30-minute window
• The transmission risk level must be at least III (3). It is determined when sharing the diagnosis codes per day according to defined criteria such as symptom status and/or symptom onset

If these criteria are not met, an encounter is not counted within the app. It is a 'non-risk encounter'. These encounters will still show up in the operating system's contact log, but do not count towards the overall risk score in the app.

If the conditions are met, the contact times are weighted depending on the signal attenuation:

• Times with an attenuation <63dB are weighted at 80%.
• Times with an attenuation >= 63dB and <73dB are weighted at 100%.
• Times with an attenuation >= 73dB and <79dB are weighted at 10%.

Based on the transmission risk level (III to VIII), a factor between 0.6 and 1.6 is determined. The weighted exposure time from the previous step is multiplied by this factor, which then results in the normalized exposure time. Finally, all normalized times of a day are added up. Ultimately, this means that several short low risk encounters can result in a red status in total. The sum of all normalized exposure times is now used to decide the final risk score:

• Sum of contact time <5 minutes: No risk exposure(s) (green).
• Sum of contact time >=5 minutes and <9 minutes: Low risk exposure(s) (green).
• Sum of contact time >=9 minutes: High risk exposure(s) (red).

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By which criteria are encounters evaluated and how do the recommendations for action differ?

The calculation of your individual risk is based on the following factors:

1. Duration of the encounter
2. Distance at the time of the encounter
3. Time that has elapsed since the encounter
4. Infectiousness (derived from information on when and whether symptoms occur).

If the calculated risk exceeds the threshold specified by the Robert Koch Institute, users will receive a notification regarding an increased risk. More information on the calculation of the threshold can be found in entry How does the app calculate the risk (version >=1.9)?.

The Corona-Warn-App has two different status indicators that indicate this risk: "low risk" (green) and "increased risk" (red).

If you see high-risk or low-risk encounters on your smartphone, it means that your smartphone and that of a person who later reported themselves as infected in the app have exchanged diagnostic keys via Bluetooth in the past 14 days. Based on the above mentioned criteria, this encounter is then classified as having an increased or low risk of infection.

If the app shows a "low risk" (green), the relevant threshold values have not been exceeded. Nevertheless, the app also informs you that your smartphone has recorded one or more encounters with (later positively tested) persons in the past 14 days and also shows on how many days this was the case. As of version 1.9.1 of the app, users will see the number of days on which risk encounters have taken place, rather than the number of encounters. In addition, the following note is displayed: "A low risk exists in particular if your encounter was limited to a short period of time or a longer distance. You do not need to worry, and there is no particular need for action."

If you get a "increased risk" (red), you should stay at home and reduce your direct contacts. Contact your general practitioner, the health department or the medical on-call service at 116117 to discuss how to proceed. You can also book an appointment directly via the 116117 on-call service's website or app (Play Store, App Store). The decision whether a so-called PCR test is performed is ultimately up to your doctor. However, both the RKI and the Federal Ministry of Health have published corresponding guidelines and recommendations. As of version 1.9.1, the app also shows the last time (within the last 14 days) an encounter with increased risk took place. You can now see an exact date to better track your contacts or behaviour on that specific day.

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I received the message that I had a low risk encounter. The next day it was gone again. Shouldn't this be deleted after 14 days?

As soon as the app downloads the current diagnostic keys (positive IDs) from the server, a check of the contact log is performed. For each of the last 14 days for which diagnostic keys are available, a separate contact log check is performed. This means that the app compares the encounters of the last 14 days with the positive IDs to check whether there has been a contact with a person who tested positive. If the message about a low-risk encounter disappears after one day, this means that the corresponding encounter was more than 14 days ago in this case.

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I got the message in the app that I had two low risk encounters. But the status indicator remained green. Should I be worried?

No, because based on the data of the risk assessment, the risk of infection is considered low because the encounter was limited to a short period of time and/or a longer distance. You do not need to worry and there is no particular need for action. It is recommended to follow the generally applicable rules of distance and hygiene. You do not need to get yourself tested after low risk encounters. Users can find the suggested behavior as well as information about the time of detection and the risk of infection in the app itself when they tap on "Low risk" with their finger.

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Are risk encounters with the same person counted several times a day?

No, because version 2 of the Exposure Notification Framework (ENF) changes the way the risk is determined. Users will be able to see the number of days that risk encounters have occurred, rather than the number of encounters.

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Is an encounter on different days with one and the same person counted several times?

Yes, that's right. Version 2 of the Exposure Notification Framework (ENF), the interface for Corona apps from Apple and Google, counts the days on which risk encounters have occurred. In other words, a person encountered yesterday and today is counted as "risk encounters on two days." A day is defined here as midnight "UTC" to midnight "UTC" of the following day.

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General

Do I have to use this app?

No. The app has two functions: It enables you to retrieve test results electronically, and it helps to identify possible exposures you have had to people diagnosed with COVID-19. You are free to decide whether to retrieve your test results, and whether you want to submit your results as diagnosis keys if your results are positive. Nothing will happen without your explicit consent.

At any point in time, you can deactivate the COVID-19 Exposure Notifications feature either in the app itself or in your device's settings, and of course you can always uninstall the app completely. When uninstalling the app, the collected exposures can be lost, see Are the exposure logs/random IDs removed from my phone when I uninstall the app?.

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Where do I find numbers and statistics about the Corona-Warn-App?

The Robert Koch Institute provides current numbers and statistics on their website (in German).

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What are the specific objectives of the Federal Government with the development of an exposure (contact) tracing app?

The main objective of the Corona-Warn-App is to notify users as quickly as possible if they have been exposed to a person diagnosed with COVID-19. From an epidemiological perspective, exposure tracing processes can be accelerated because the Corona-Warn-App helps to notify people at risk more quickly.

This means that potential infection chains can be identified and interrupted earlier. This can also help to relax the existing restrictions in order to normalize social life.

In addition to essential hygiene and behavior rules to prevent infection and many other measures, such as increasing the number of tests and improving exposure tracing through public health authorities, the Corona-Warn-App is another element in the fight against the coronavirus pandemic.

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What were the reasons for favoring the decentralized approach to exposure tracing?

In April 2020, a scientific debate emerged on the key concept "centralized versus decentralized data storage", which was conducted under the public eye. In addition to plausible arguments in terms of content, a partly ideological debate on centralized storage developed, which had the potential to jeopardize confidence in this technological approach.

A loss of confidence among the public would have endangered all the efforts of identifying and breaking infection chains early using digital support. For this reason, the Federal Government took action and adapted a decentralized approach as the project philosophy.

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Was a risk and cost/benefit evaluation of the two variants (centralized/decentralized) carried out, and if so, can this evaluation be viewed?

A scientifically-reliable evaluation is not available due to the complexity of this topic, the lack of practical experience with the underlying technologies, and for the reasons mentioned above.

Both approaches have advantages and disadvantages in terms of usability and have been intensively discussed with expert personnel from university and non-university research institutions, the Robert Koch Institute, the Federal Office for Information Security (BSI) and the Federal Commissioner for Data Protection and Freedom of Information (BfDI).

The further development of the Corona-Warn-App will also be closely accompanied by scientific research.

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What specific constraints has the German government imposed on the contractors, SAP and Deutsche Telekom, for the development?

Besides the decentralized storage of encounters using the interfaces provided by Google and Apple, the discussions also focused on the publication of the developed software components under an open source license.

The app will be available in the official Google and Apple app stores.

An additional requirement for the development process was the early and intensive involvement of the BfDI and the BSI, as well as close coordination with these bodies.

As this is an agile development process, requirements are constantly evolving.

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Where can I find information, ask questions, or discuss topics regarding the Corona-Warn-App that are not development-related?

The open source project for the Corona-Warn-App on github.com/corona-warn-app and the website coronawarn.app is all about the open source development of the app. For information about general topics, legal matters, and using the app, you can also see bundesregierung.de/breg-de/themen/corona-warn-app/corona-warn-app-englisch. For questions related to these topics, please use the contact form of the Federal Government.

You can also read information about using the app and about privacy directly from the app. In the app menu, go to App Information, and there, choose Terms of Use and Data Privacy Information.

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Is there a central entity in control of all exposure events?

The app itself does not store any information about individual potential exposure events. The Exposure Notification System, on which the app is based, stores the visible Rolling Proximity Identifiers (RPIs) on the devices that are located in close proximity and within a defined time period. Even if the central server infrastructure is compromised, this information cannot be linked back to a device without having access to it in the first place. Even then, the app itself cannot access the RPIs. Diagnosis keys can only be accessed with user consent and then only for a short period of time. Information that links diagnosis keys and connection metadata is removed before this data is processed.

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Who operates the app backend?

The backend of the app is operated by Deutsche Telekom. Open Telekom Cloud (OTC) is used here.

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How do the server and device communicate with each other?

You can find more information in our Solution Architecture Document.

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Contact Journal

Since release of the contact journal function, we continuously received suggestions for changes and improvements. All those ideas will be reviewed technically and together with the client regarding:

• User friendliness of the UI,
• extension by functions (e.g. recording of additional parameters),
• technical feasibility (or the effort required for implementation), and
• Benefit for the health authorities (if the user decides to share the contact journal and provide this information)
• legal framework and limits

The number of comments regarding the contact journal confirms the active support of our community. We are pleased this new function is positively received by the app's users.

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More information on how to use the contact journal can be found in this blog post.

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Open Source

Why are we following an open-source approach?

We believe that the success of the app depends directly on user acceptance and trust. With an open source approach, the full source code for the app and the infrastructure are freely available without access restrictions. In this way, we create the transparency necessary for a strong basis of trust.

Furthermore, the open-source approach gives the broader public and the developer community the opportunity to actively contribute to the app’s success, for example, through reviews and pull requests.

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Can I really see all source code of the project?

Yes. All code central to risk identification and propagation functionality is available openly on GitHub. Reviews are possible before and after the app is released. Questions about topics such as security, data privacy will be clarified with the community. Each person can create their own build of the app and test it. Apart from the source code, we also discuss central issues there. The discussion posts remain publicly available on the GitHub.

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How will the development status in GitHub be uploaded to the app stores?

The app is developed using standard tools (such as Xcode and Android Studio) and uploaded to Apple App Store and Google Play Store.

We will be able to publish information as soon as it is available on the issue as to whether the code in GitHub is really the same as that in the app in the respective app stores ('reproducible builds'). You can find further information on the progress of this issue in the respective GitHub issue.

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How can the development community contribute to the project?

The open-source project uses GitHub, a globally known online service that hosts software development projects on its servers. Anyone interested can get involved in the project here, for example, by removing mistakes in the source code, helping with the documentation, raising questions or commenting on the project.

Collaboration within the community follows a defined code of conduct. You can find all the guidelines for participation here.

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Why are you using GitHub instead of a different platform?

We believe that GitHub is a well-established, respected platform for open-source projects. It is the world's largest open-source platform, with more than 40 million users and over 100 million repositories, over 30 million of which are publicly accessible.

If someone does not want to create a GitHub account, they can view the source code without an account.

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What code of conduct applies?

Successful development in a productive, collaborative community is only possible through mutual respect. All members of the project must follow a Code of Conduct.

Any member can report violations of the code of conduct to the project managers or to corona-warn-app.opensource@sap.com. Violators may face consequences such as warnings or even exclusion from participating in the project.

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Privacy and Security

Can data privacy be guaranteed?

Decentralized data storage on user devices guarantees data privacy.

We are working very closely together with experts from the data privacy community and coordinating with one another throughout the development process. We also prepared a separate document dedicated to data security, which is published here on coronawarn.app.

Furthermore, the open-source approach of the source code enables the community to review the functionality of the app and to leave comments.

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Which data will be saved and who can access this data through Bluetooth?

Bluetooth is used to send constantly changing random IDs from other devices that have installed the app. No personal, geo-location, or other location data is sent or stored.

Using the Exposure Notification API from Google and Apple, the random IDs remain in a secure area of the device's operating system. The matching, which determines whether someone has been exposed to an infected person, is performed on the local device. The device does not send any data for matching.

As soon as a user is diagnosed with COVID-19, they're asked to share their temporary exposure keys from the last 14 days. These keys can only be accessed by the Exposure Notification API if the user actively gives consent.

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Can I be identified as COVID-19-positive by network traffic monitoring?

State of the art and well-established encryption mechanisms, for example using HTTP over TLS (HTTPS), ensure that messages are not readable for outside viewers. Metadata is removed before processing user data for the transmission of diagnosis keys. This prevents data from being linked together at database level.

Furthermore, various additional technical measures will be introduced shortly, for example, by randomly creating and sending false notifications that will be discarded on the server side. These false notifications cannot be distinguished from valid notifications and create a type of background noise. The transmission of TANs and upload of real infection data cannot be distinguished from this background noise. So, even with monitored network traffic, plausible deniability is still possible.

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How do you guarantee that I remain anonymous when using the Corona-Warn-App?

Devices in close proximity to yours collect “rolling proximity identifiers” (RPI). These are IDs that guarantee data privacy and change constantly in short intervals, thereby preventing devices from being tracked. Apart from these IDs, other devices in close proximity cannot retrieve any other information from your device. These IDs can only be linked to pseudonymous diagnosis keys, which are needed to perform risk identification. A connection with user IDs or your device's International Mobile Equipment Identity (IMEI) is not possible.

Since these IDs change every 10 - 20 minutes, a person sitting next to you every day in a bus could not link you to an ID even if the list of available RPIs was visible. The only time you must identify yourself is if you give your consent to upload your diagnosis keys via TeleTAN. This identification is just for verification reasons and does not disclose any other personal information. You could even use a different device to upload your diagnosis keys instead of the device on which the Corona-Warn-App is installed.

Why were dummy keys (fake diagnostic keys) initially created and used?
A very small number of dummy keys could possibly result in transmitted diagnostic keys being assigned to a single user. To minimise this risk, fake diagnostic keys (dummy keys) were initially generated. This increased the number of diagnostic keys in the system in order to minimise the described re-identification risk.

Why is it now possible to do without the generation and use of dummy keys (fake diagnostic keys)?
Due to the current increase in the number of infections, many diagnostic keys are already being managed in the CWA. Therefore the risk of re-identification is currently considered very low. With the connection of the CWA to the European Federation Gateway Service (EFGS), the number of diagnostic keys in the system will increase even further, as diagnostic keys from users in other countries will also be added. For this reason, the generation and use of fake diagnostic keys (dummy keys) can be easily avoided.

Will dummy keys (fake diagnostic keys) be used again if the corona pandemic should abate?
If no better alternatives are found in the meantime, the generation of dummy keys (fake diagnosis keys) can be activated at short notice if required.

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Can transmitted information be linked back to me and my past activities?

Your device generates temporary exposure keys. These are generated randomly and only on your device. It is cryptographically not possible to trace two randomly-generated diagnosis keys back to a device without having further information or gaining access to the device's secure storage. In addition, only keys from the last 14 days are reported. It is not possible or planned to track any other data.

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Is movement or exposure data saved centrally?

Your location and data about your possible exposure to people diagnosed with COVID-19 are never stored centrally. At any given point, the system is only aware that a diagnosis key belongs to a person diagnosed with COVID-19. The system does not know who this person met, nor when or where the encounter took place. No identification is required for the app to identify that an encounter took place. You only have to identify yourself to retrieve test results and to submit your diagnosis key. Linking the app to any social media profiles is not, and will not in future, be implemented in this project.

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What personal data is stored in the app?

As mandated by the General Data Protection Regulation (GDPR), data minimization is a paramount principle in the implementation of the app. The only inputs that users can and have to provide to the app are:

• Permissions for using the Exposure Notification System
• TANs for test result verification
• Consent to upload daily diagnosis keys

Location data is not and cannot be collected by apps using the Exposure Notification System. Diagnosis keys are only stored centrally for the epidemiologically relevant period of 14 days and removed automatically after that period.

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Is Bluetooth really secure? What can I do to prevent attackers from introducing malicious software into my device?

To increase the security of your device in general, you should always install the latest security updates as well as the latest operating system version for your device. By doing this, you make sure that your device fulfills the latest security specifications of the Bluetooth protocol that are available.

Especially Android systems should always be on the latest Android version (typically published in the previous month, see Android Security Bulletins). Here you can find detailed information on how to find the latest Android version for your device: Check & update your Android version.

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Doesn’t the open-source approach, which involves publishing the source code, put cybersecurity at risk?

On the contrary: the open-source community increases the level of security of the software, because the source code is open to all and anyone can download it and comb through it line by line.

We believe that security is not helped by a lack of transparency. That is why we are taking an open-source approach.

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Resolved

Can I enter a test result from a Corona rapid test (Schnelltest)?

Update
Since version 2.1 it is possible to enter the test result of a rapid antigen test into the app. More information can be found in this blog post and in the FAQs to rapid antigen tests.

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No, entering results from rapid tests is currently not supported by the Corona-Warn-App.

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[Apple/iOS]: Risk exposure can no longer be activated after updating to iOS 14

After updating to iOS 14, some users report that risk exposure has been disabled and can no longer be turned on.

This problem has already been reported to development and they are working on a solution. To be able to use the app to its full extent until the bug is fixed, please follow these steps:

'Settings' > 'WiFi' > Switch 'WiFi' off.

'Settings' > 'Exposure notifications' > 'Active region' (Corona-Warn-App) > 'Corona-Warn-App' > Switch 'Share exposure information' off and on again.

'Settings' > 'WiFi' > Switch 'WiFi' on again.

If the error still occurs although you have performed all steps, you have to reset and reinstall the application once. Your collected random ids will not be lost (see also here). However, it will take 24 hours until the app resumes the data collected so.

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[Google/Android]: CAUSE: 2001, trying to establish a secure connection to the server

The T-Systems Enterprise Services GmbH, T-TeleSec GlobalRoot Class 2 security certificate may be disabled on your device. This is a known cause to trigger the notification:

'CAUSE: 2001 Something went wrong. An error occurred while trying to establish a secure connection to the server.'

Follow these steps in order to activate the security certificate. The exact path depends on the device.

1. 'Settings' -> 'Biometrics and security' -> 'Other security settings' -> 'View security certificates' -> 'SYSTEM'
2. Scroll down to T-Systems Enterprise Services GmbH, T-TeleSec GlobalRoot Class 2
3. Enable the certificate using the slider

Should this procedure not solve this issue, please write a comment here: cwa-app-android/issues/968.

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[Google/Android]: Notes on devices from Huawei or Honor

UPDATE
The problem was solved by the device manufacturers via a patch. Please install the latest updates for your device.

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For devices from Huawei or Honor, in addition to switching on the Prioritized Background Activity, additional settings may be necessary to improve the reliability of the background update, and to prevent unexpected crashes of the Corona-Warn-App when starting the app. This applies in particular to older devices with EMUI 4, but also to newer devices.

According to current information, a system update seems to be available for newer Huawei devices that is explicitly intended to fix the problems with Corona-Warn-App.

The GitHub community has compiled suggestions for making additional settings and has also linked information about the system update. You can find all the details in this GitHub issue.

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[Apple/iOS]: Notes on the Low Power Mode on iOS devices

UPDATE
Since February 5, 2021 the minimum required version of the Corona-Warn-App is 1.5.3. This version requires iOS 13.7 or later. When using these iOS versions, the Corona-Warn-App is not negatively affected by activating Low Power Mode.

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If your device runs on iOS version 13.6.1 or later, the functionality of the Corona-Warn-App is not negatively affected by the Low Power Mode. On devices with an earlier iOS version, Low Power Mode may cause problems with updating the risk status in the background. We therefore ask you to update the iOS version of your device to 13.6.1 or higher if you want to use the Low Power Mode.

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My exposure log shows multiple, simultaneous checks for exposures. Is that an error?

UPDATE
As of version 1.6.0 of the Corona-Warn-App, there are no longer separate checks for each day. Instead, the app performs a single check on all available diagnosis keys from the past 14 days when an update is downloaded from the server.

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When the app downloads the current diagnosis keys from the server, a check of the exposure log is performed. During that process, a separate check is performed for each of the last 14 days, for which diagnosis keys are available. It is therefore not an error that multiple, seemingly simultaneous entries are visible in the exposure check history. You can further click on the details of each check to see that different amounts of keys were provided for each of them.

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[Apple/iOS] 'ExposureDetectionIsAlreadyRunning' in CWA version 1.6.1

UPDATE
This issue has been fixed in version 1.7.1.

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The notification 'ExposureDetectionIsAlreadyRunning' can be ignored. The CWA is still working correctly and this issue will be solved with a future release.

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[Apple/iOS]: Exposure Check Failed after updating to version 1.6.0

UPDATE
This issue has been fixed in version 1.6.1.

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After an update to app version 1.6.0, you might get the error 'Exposure Check Failed', even though there was a successful check in the past 24 hours. We are working on a solution for this error. In the meantime, try restarting your app. This helps in most cases.

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[Apple/iOS]: Migrating to new phone and backup and restore - app does not work

UPDATE
This problem has been solved with version 1.5.0.

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If you transfer your data to a new iPhone using iTunes, or restore a backup, the app does not work properly. On the start screens, you end up in a loop, or the exposure logging cannot be activated. The risk status is not displayed.

This is a known problem with backing up the random IDs, see also https://www.coronawarn.app/en/faq/#backup.

Please reinstall the Corona-Warn-App on your new iPhone.

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[Apple/iOS]: 'COVID-19 exposure logging... - Weekly Update'

UPDATE
The behaviour of the iOS notification regarding exposure notifications has been changed with iOS version 13.7. A notification is now displayed in a monthly interval. It can be deactivated in the iOS settings:

1. 'Settings' -> 'Exposure Notifications'
2. Deactivate 'Monthly Update'.

We therefore ask you to update to the newest iOS release.

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This is a general notification, which does not mean that risk encounters have been identified. It is not a message or function of the Corona-Warn-App. Apple's Exposure Notification System (ENS) sends this notification and displays the icon. Apple's ENS provides information about any encounters with app users who were tested positive - without making a statement as to whether or not it was a critical encounter according to the Robert Koch Institute's algorithm. For example, encounters are also displayed in case the distance was more than 8 meters or in case it only lasted a few minutes. This means that the 'Weekly Update' only provides information about technical procedures of the ENS that are insufficient for an actual risk calculation. A reliable risk calculation takes place exclusively in the Corona-Warn-App under the scientific framework of the Robert Koch Institute. You can view your current risk status directly in the Corona-Warn-App.

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[Google/Android]: Error when communicating with Google API (39508)

UPDATE 16.01.2021
The error notification now reads "Limit already reached". Please see the corresponding FAQ entry for further information on this issue.

UPDATE
This bug has been fixed in version 1.5 of the Corona-Warn-App. We therefore ask you to update the app accordingly.
IMPORTANT:
After updating to version 1.5 it will take up to 24 hours until the error is gone.

If you are still receiving the error after updating to 1.5 and waiting 24 hours, please report it in the associated GitHub issue.

---

The notification indicates that the Corona-Warn-App has called the Exposure Notification System too often to downloaded the keys from the server and match them with the locally stored random IDs. This is how it can be determined if there were exposures to persons who reported positive.

It can be triggered by various other errors, but is always a consequence of them, not the root cause. The error should disappear after 24 hours. Please keep your app closed for this timeframe.

If it still occurs afterwards, please comment in the associated GitHub issue and provide the following information about your phone:

• Device name
• Android version
• CWA App version

We ask you to not de-install the app or to reset the data of Google Play Services, because this can remove the logged exposures, and it will not resolve this issue. Additionally, we ask you to not delete the app data of Corona-Warn-App, as this will also not resolve the issue in this case, but you might lose other important data, like a formerly registered COVID-19 test.

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[Google/Android]: Cause: 9002 Something went wrong (timeout)

UPDATE
This bug has been fixed in version 1.5 of the Corona-Warn-App. We therefore ask you to update the app accordingly.

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If, when opening Corona-Warn-App, the current keys of positively tested users are to be downloaded from the server (because automatic data synchronization was not yet carried out on that day) and no internet connection can be established, you may receive the following error message: 'Cause: 9002, Something went wrong. timeout'. A 'java.net.SocketTimeoutException' is given as the cause under 'Details'. There are two different known causes that can lead to this error:

1. The internet connection is still being established. If you have just switched on previously deactivated data connections (Wi-Fi or mobile) or restarted your phone and immediately open Corona-Warn-App, the internet connection may not have been fully established yet. There are also special apps that only enable data connections when the screen is switched on. In these cases the error message can occur. Solution: If the internet connection was deactivated or interrupted, wait a few seconds after switching on the internet connection before opening Corona-Warn-App. If you use an app to control data connections, set it up so that data connections in the background are enabled for Corona-Warn-App.
2. The internet connection is blocked. This can be the case if you have either manually restricted data connections in your phone’s settings or if data connections for Corona-Warn-App have been automatically deactivated by your antivirus app and/or firewall. Solution: Enable data usage in general as well as background data and unrestricted data usage in the settings of your phone for Corona-Warn-App. If you use an antivirus app and/or firewall on your phone, set it up so that there are no data usage restrictions for Corona-Warn-App.

Please refer to GitHub issue 998 for more information.

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[Google/Android]: Cause: 9002 Something went wrong (sqlite)

UPDATE
This bug has been fixed in version 1.5 of the Corona-Warn-App. We therefore ask you to update the app accordingly.

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On some phones (for example, Huawei P20 Pro), there could be problems when accessing the encrypted area of the app database, where the info for the risk status and the last updates are stored. Usually, this error displays a Cause: 9002 message with hints to the database used, SQLite, sqlite_master, a security exception, or an error with the decryption. It can sometimes be that you can't open the app.

We're working on identifying the cause and fixing it then. For details, see https://github.com/corona-warn-app/cwa-app-android/issues/642. There, we will keep you updated for fixing the error and additional hints.

If your phone type is not yet covered in the GitHub issue, write us the type in a comment. This helps us to determine the cause. If the GitHub issue doesn't cover your cause 9002 error, create a new issue.

If you can no longer open the app, please read the section 'Corona-Warn-App is closed immediately after starting'.

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[Google/Android]: Corona-Warn-App is closed immediately after starting

UPDATE
This bug has been fixed in version 1.5 of the Corona-Warn-App. We therefore ask you to update the app accordingly.

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If Corona-Warn-App is unexpectedly terminated due to an error in the operating system or aggressive energy-saving measures taken by the phone, it may happen that the Corona-Warn-App can no longer access its encrypted databases when it is restarted. In this case, it is closed immediately on start. Sometimes the error Cause: 9002 Something went wrong (sqlite) was displayed before.

We are working flat out to find a solution to the problem.

The GitHub community has developed an emergency solution that brings the Corona-Warn-App up and running again without uninstalling it. However, since data can be lost in this case (e.g. registered COVID-19 tests for online querying of the test results), you should only use this emergency solution if no other measures were helpful (in particular suggestions from the technical hotline or from supervisors of the Corona-Warn-App in the Google Play Store), and you have fully taken note of the information on the emergency solution in the GitHub issue.

Find the emergency solution in the GitHub issue here.

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[Google/Android]: Exposures are displayed for more than 14 days

UPDATE: This Issue was resolved in version 1.2 of the Corona-Warn-App. Exposures are displayed for up to 14 days after you encountered the user who then uploaded a diagnosis key using the Corona-Warn-App.

For some phones running Android, the exposures currently are displayed for more than 14 days. We're working on fixing this display error. You'll find up-to-date information in GitHub issue 911.

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[Google/Android]: 0 keys displayed

UPDATE: This display error was resolved by a Google Play Services update, see this GitHub comment.

This is a known display error. The app still works as intended. We're currently working to solve this problem together with Google.

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When will the app be ready?

The app is available since June 16, 2020. You can download it from Google Play Store and Apple App Store. The development progress can still be tracked in the code repositories.

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[Apple/iOS]: Problems after updating to iOS 13.6

UPDATE: Apple has now released iOS version 13.6.1, which fixes this error. Please update your phone to iOS 13.6.1.

After updating to the iOS version 13.6, exposure logging couldn't be activated on some iPhones because exposure logging was seemingly not available in their region. For details, see GitHub issue https://github.com/corona-warn-app/cwa-app-ios/issues/911.

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[Apple/iOS] I cannot open the app

UPDATE: App version 1.2.1 is now available and resolves this issue. Please update your app.

Unfortunately, an error was introduced with the latest update (1.2.0): Many users were not able to open the app.

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[Google/Android] The explanation for a risk encounter on the low risk card is contradictory

UPDATE: This error has already been corrected. The correction is available with app version 1.2.1. Please update the app.

With the latest update (1.2.0), a misleading explanatory text was introduced for a low risk of infection. If there was an exposure and the app still shows a low risk for you, the risk of infection is still ranked as 'low' and not as 'increased' (as described in the current text).

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[Apple/iOS]: Wrong number of active days

Update: This display error is resolved by now. Please update the Corona-Warn-App to the latest version. The app will now count up the number of active days, until the 14 active days are reached, as intended.

When counting the active days, an error is displayed currently: When '14 of 14 active days' is reached, the number of active days doesn't display 14 out of 14, but keeps displaying 13 out of 14 active days or fewer.

This is only a display error. The Corona-Warn-App continues to work as intended, that means, the IDs are still exchanged and the exposure logging still works. No data is lost. Technically, it is a rounding error that displays when the number of active days of the exposure logging does not increase any more, but stays 14 days. When the exposure logging was inactive in any way, even for a short amount of time, the counter stays at a lower number of days, for example, 13 active days.

Exposure logging can be deactivated, for example, by the following:

1. Bluetooth was deactivated, even for a short amount of time
2. Background updates for the app where not active, so that exposure logging was not done continuously
3. Flight mode was active, even for a short amount of time
4. The smartphone was turned off
5. The smartphone was restarted

For detailed information, see this comment on GitHub.

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[Google/Android]: Wrong number of active days

UPDATE: This display is updated in the meantime. If nonetheless another day count displays, see My exposure log shows checks for less than 14 days.

When counting the active days, an error is displayed currently: When '14 of 14 active days' is reached, the number of active days doesn't display 14 out of 14, but keeps displaying 13 out of 14 active days or fewer.

This is only a display error. The Corona-Warn-App continues to work as intended, that means, the IDs are still exchanged and the exposure logging still works. No data is lost. Technically, it is a rounding error that displays when the number of active days of the exposure logging does not increase any more, but stays 14 days. When the exposure logging was inactive in any way, even for a short amount of time, the counter stays at a lower number of days, for example, 13 active days.

Exposure logging can be deactivated, for example, by the following:

1. Bluetooth or the location service were deactivated, even for a short amount of time
2. Background updates for the app where not active, so that exposure logging was not done continuously
3. Flight mode was active, even for a short amount of time
4. The smartphone was turned off
5. The smartphone was restarted

It is planned that this will be resolved with the next release.

For detailed information, see this comment on GitHub

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Why does the app stop at 14 of 14 days saved? What does 14 of 14 days save actually mean?

UPDATE: This display is updated in the meantime. If nonetheless another day count displays, see My exposure log shows checks for less than 14 days.

The Corona-Warn-App logs exposures for the past 14 days. Older exposures are not relevant for the risk assessment and will therefore be discarded. Hence, the app will always show "14 of 14 days saved" if it was active for the entire time frame. The count does not start over after 14 days. If exposure logging is active and a risk status is being displayed, the app is working as expected.

If you temporarily deactivate the app after 14 days, the displayed number can jump back to 13 (or fewer) active days. This can be triggered by the following activities:

• Disabling bluetooth
• Disabling the background app refresh so that risk assessment could not be performed
• Enabling flight mode
• Turning off your smartphone
• Restarting your smartphone

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[Google/Android]: Error when communicating with Google API(10)

UPDATE 14.01.2021
Should you experience this issue, please write a report here: cwa-app-android/issues/1962.

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UPDATE: This error is resolved by version 1.5 of the Exposure Notification System. For details about your ENS version, see Which version of the COVID-19 Exposure Notification System is currently installed?

This error, in connection with missing risk identification, is currently fixed together with Google. Exposure logging works as intended. Please do not uninstall the app, because this can remove the logged exposures, see also https://www.coronawarn.app/en/faq/#delete_random_ids.

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[Apple/iOS]: ENErrorDomain-Error 11

UPDATE: Although Apple stated that this Issue has been fixed with iOS 13.6, it's currently appearing again on devices which run iOS 14 or higher. To fix it please open the iOS settings and go to 'Exposure Notification', scroll down to the bottom and click 'Turn Off Exposure Notifications' and turn it back on again.

The ENErrorDomain 11 error is thrown by Apple's Exposure Notification System, which is used by the Corona-Warn-App.

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[Apple/iOS]: ENErrorDomain-Error 5

UPDATE: The ENErrorDomain 5 error is thrown by Apple's Exposure Notification System, which is used by the Corona-Warn-App. According to Apple, the cause is already fixed, and therefore, it shouldn't occur any more. If the error still occurs, please be patient until the change reaches your device.

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[Apple/iOS]: I sometimes get the following notification: 'Exposure Notifications Region Changed. COVID-19 Exposure Notifications may not be supported by "Corona-Warn" in this region.'

UPDATE: After you updated to iOS version 13.6., this message is gone.

This message is issued directly by the Exposure Notification System of the operating system. You can choose 'OK' to confirm the message, exposure logging works as intended. To check this, you can also navigate to 'Settings' > 'Privacy' > 'Health' > 'COVID-19 Exposure Logging' (iOS 13.7 or higher: 'Settings' > 'Exposure Notifications' > 'Exposure Logging Status') on your device to check the status. This is an iOS bug and Apple is already working on a solution, which is expected to be delivered with the next iOS update. Please open the Corona-Warn-App once again to make sure that the background app refresh continues to work.

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[Apple/iOS]: Not enough memory for the contact protocol

UPDATE: This error is raised by the operating system. After you updated to Apple iOS version 13.6., this error should be gone.

The Corona-Warn-App uses just about 20 MB of smartphone storage. The size can vary slightly due to updates. In addition, the app caches some data.

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[Google/Android]: While setting up the app, I’m getting the following error: 'CAUSE: 3. Something went wrong. Error when communication with Google API (17).' What does this mean?

UPDATE: This error is fixed in the meantime.

This error can occur when you activate exposure logging for the first time or later in the settings or on the main screen of the app. It means that your device cannot log exposure for one or more of the following reasons:

• Google Play Services are outdated.
• The app is not available with Google Play for your country. See this FAQ for the supported country versions.
• You haven’t installed Corona-Warn-App via the official Google Play Store.
• Your device has been modified (e.g. by rooting).
• You have multiple user accounts on your device and the user that you use Corona-Warn-App with doesn’t have administrator rights.
• The manufacturer of your device hasn’t made Google Play Services and Google Play Store available for your device. This affects some models by Huawei und Xiaomi, for example.
• Google Mobile Services are outdated.

Troubleshooting

Many affected users were able to get rid of this error through the following steps:

1. Update your Google Play Services to the latest version. See: Google Play Services. In the device settings under 'Apps & notifications' > 'Google Play Services' > 'Advanced', you can check your version at the bottom. Please also see the note on Google Mobile Services at the bottom of this answer.
2. Clear the cache of the Google Play Services in the device settings under 'Apps & notifications' > 'Google Play Services' > 'Storage' > 'Clear cache'.
3. Change your Google Play country to Germany as described here: Change your Google Play country.
4. Check if your device generally supports exposure logging in Germany. In the device settings under 'Google' > 'COVID-19 Exposure Notifications', Corona-Warn-App should be listed.
5. Make sure that the user account that you’re using on your device has administrator rights. In the device settings, go to 'System' > 'Advanced' > 'Multiple users'.
6. Before you install Corona-Warn-App make sure that you’re connected to the internet and that you have activated Bluetooth and Location (see also here).
7. Restart your device.
8. If nothing else worked, because doing so could remove the already collected random IDs (see https://www.coronawarn.app/en/faq/#delete_random_ids): Uninstall the Corona-Warn-App and reinstall it from the Google Play Store (Corona-Warn-App).

If the error persists even though you went through all steps listed above, Possibly a short wait is necessary for your device to activate Exposure Logging. Please close Corona-Warn-App and wait for two hours before trying again.

Note on Google Mobile Services: For Corona-Warn-App to work, Google Mobile Services has to be automatically updated on the device by Google. You cannot manually trigger this update. If you have already updated the Google Play Services as described above, you have to wait for the automatic update of Google Mobile Services. Try using the app again the next day.

We’re constantly improving the app and will try to remove possible app-related causes of this error.

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[Apple/iOS]: In my COVID-19 Exposure Logging settings it says: 'Corona-Warn has checked your log of collected random IDs 0 times over the past 24 hours.' Does this mean that exposure logging isn’t working?

UDPATE: This notification is no longer displayed since the diagnosis keys are available on the server.

Exposure logging is working, don’t worry. You can find this iOS note under 'Settings' > 'Privacy' > 'Health' > 'COVID-19 Exposure Logging' (iOS 13.7 or higher: 'Settings' > 'Exposure Notifications' > 'Exposure Logging Status'). It means that the back-end server has not sent any diagnosis keys to your device yet. Thus, the Corona-Warn-App hasn’t received any keys to check against the collected random IDs on your phone. As soon as persons diagnosed with COVID-19 have uploaded their diagnosis keys, this check is triggered.

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Exposure Notification Express (ENE)

Exposure Notification Express (ENE) was additionally developed by Google and Apple to support health authorities worldwide who do not yet have an app and cannot or do not want to develop an app themselves. ENE simply provides standardized COVID-19 notifications, but does not digitize the process to the test result.

Although risk encounters can be displayed, the diagnostic keys cannot be transmitted without further verification if the test result is positive. Nor can test results be transmitted with ENE.

For the German Corona-Warn-App (CWA), the introduction of Exposure Notification Express does not currently change anything. Regions that operate an app adapted to their own needs will continue to receive the encounter notifications from the Exposure Notification System directly and exclusively. In Germany, all exposure notifications are routed exclusively to the CWA. The high German standards for data protection apply. Risk assessment in Germany is carried out exclusively according to the epidemiological guidelines of the Robert Koch Institute (RKI). Users receive personal support from the hotlines if required.

According to current knowledge, the own app instead of the standard solution ENE offers countries the following advantages:

• Flexible verification process
• Integrated laboratory connection, faster notification process
• Data protection conformity
• Legal conformity, e.g. age rating
• EU interoperability with legal certainty and data protection
• Integration of hotlines
• Backend servers still have to be operated
• Parameterization (e.g. when an encounter is evaluated as a risk does not come from Google/Apple, but can be defined by each country)

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When were the FAQ last updated?

Updated 2021-06-16

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