Unable to Sign In to Microsoft Teams on Windows – Security Key Prompt Appears After Authenticator MFA

Karagün, Oguz Can 0 Saygınlık puanı
2026-06-12T07:37:00.1166667+00:00

Hello,

I am experiencing an issue when trying to sign in to Microsoft Teams on my Windows PC using my university account:

Account: @stud.fra-uas.de

Issue Description

I can successfully enter my username and password, and I also receive the MFA code in the Microsoft Authenticator app on my phone. After approving the sign-in and entering the code, instead of logging me into Teams, Windows displays the following message:

"Insert your security key into the USB port."

A Windows Security popup appears asking for a physical security key (USB/FIDO key), even though I have never configured or used a security key for this account.

Additional Information

  • I can sign in successfully on my phone using the same account.
  • Microsoft Authenticator is working correctly and I receive MFA notifications/codes.
  • The problem only occurs on my Windows computer.
  • I have already tried closing and reopening Teams.
  • The sign-in process always ends with the security key prompt shown in the attached screenshot.

Questions

  1. Why is Windows asking for a security key after I have already completed MFA with Microsoft Authenticator?
  2. Is there a way to force Teams or Windows to use Microsoft Authenticator instead of a security key?
  3. Could this be caused by a Windows Hello, WebAuthn, or cached credential configuration on my PC?
  4. What troubleshooting steps can I take to remove this security key requirement and sign in normally?

Any help would be greatly appreciated.

Thank you.Hello,

I am experiencing an issue when trying to sign in to Microsoft Teams on my Windows PC using my university account:

Account: @stud.fra-uas.de

Issue Description

I can successfully enter my username and password, and I also receive the MFA code in the Microsoft Authenticator app on my phone. After approving the sign-in and entering the code, instead of logging me into Teams, Windows displays the following message:

"Insert your security key into the USB port."

A Windows Security popup appears asking for a physical security key (USB/FIDO key), even though I have never configured or used a security key for this account.

Additional Information

  • I can sign in successfully on my phone using the same account.
  • Microsoft Authenticator is working correctly and I receive MFA notifications/codes.
  • The problem only occurs on my Windows computer.
  • I have already tried closing and reopening Teams.
  • The sign-in process always ends with the security key prompt shown in the attached screenshot.

Questions

  1. Why is Windows asking for a security key after I have already completed MFA with Microsoft Authenticator?
  2. Is there a way to force Teams or Windows to use Microsoft Authenticator instead of a security key?
  3. Could this be caused by a Windows Hello, WebAuthn, or cached credential configuration on my PC?
  4. What troubleshooting steps can I take to remove this security key requirement and sign in normally?

Any help would be greatly appreciated.

Thank you.

Microsoft Teams | Eğitim için Microsoft Teams | Kaydolma ve Oturum açma | Oturum açın
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  1. Anonim
    2026-06-12T08:28:29.8733333+00:00

    *I noticed that you posted your question in English, so I’ll continue communicating in English for clarity. However, if you would prefer to switch to Turkish, please feel free to let me know and I’ll be happy to accommodate. 

    Hello Karagün, Oguz Can,

    Thank you for your message, and I understand how this sign-in issue can be frustrating.

    To help me better understand the situation, could you please confirm whether you are able to sign in to other Microsoft services (such as Outlook or Office.com) without any issue? Or does the same security key prompt appear there as well?

    I would also like to check if you are currently signing in using the Teams desktop application or through a web browser.

    If you are using the desktop app, could you please try clearing the Teams cache by following this guide: Clear the Teams client cache - Microsoft Teams | Microsoft Learn

    After that, please try signing in again and check if the issue persists.

    If the issue still occurs, I recommend uninstalling the Teams app and reinstalling it, then testing again.

    Additionally, if possible, could you please share a screenshot of the security key prompt you are seeing? This will help me better understand the exact behavior and assist you more effectively.

    Thank you very much for your cooperation, and I look forward to your update.

    Best regards,

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

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