Authenticator app

Question

Cannot log into account after installing Authenticator app on new phone. Kept asking to authenticate using mobile app.

How can I authenticate the authenticator mobile app?

Answer 1

When a new phone is set up, the Microsoft Authenticator app on that device is not automatically trusted for existing accounts. The account must be reconfigured for MFA or passwordless sign-in so the new app instance becomes the approved method.

Use these steps depending on what is still accessible:

1. If access to the account via browser or old device still exists
   • Sign in to the account in a browser.
   • Go to the security verification page for the work/school account: Additional security verification at https://account.activedirectory.windowsazure.com/proofup.aspx?proofup=1.
   • Remove the old phone as an MFA method: delete the old phone or old Authenticator registration from Security info.
   • Select Add sign-in method → choose Phone or Authenticator app.
   • On the new phone, install and open Microsoft Authenticator, then follow the prompts to add the account (scan the QR code or sign in as instructed).
   • Complete the verification prompts so that the new Authenticator app is registered for MFA.
2. If only a new phone is available and the app shows errors during setup
   • Ensure the app is updated to the latest version and that notifications are enabled.
   • Confirm the device has internet connectivity and correct date/time.
   • If using passwordless sign-in on Android and seeing partial setup errors, verify:
     • Push notifications are enabled.
     • Google Play Services and Google Play Store are installed and enabled.
     • A PIN or biometric is required to unlock the device and hardware encryption is enabled.
     • In Authenticator → Settings → Device Registration, confirm the work or school account is registered and joined, then re-enable passwordless for the account.
3. If completely locked out and no other MFA method works
   • For personal Microsoft accounts, use the account recovery and password reset options provided on the sign-in page.
   • For work or school accounts where the user is not the only admin, contact the organization’s IT admin to reset MFA or remove the old Authenticator registration.
   • If the user is the only administrator on a tenant and cannot sign in at all, a support request with Microsoft’s Data Protection team is required (via Microsoft Support phone channels) so they can verify identity and reset MFA from their side.

Once the old registration is removed and the new phone is added as a sign-in method, the Microsoft Authenticator app on the new device becomes the active authenticator for the account.

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References:

• Use a screen reader to set up and troubleshoot multifactor authentication
• Troubleshoot problems with Microsoft Authenticator
• Authentication methods in Microsoft Entra ID - Microsoft Authenticator app
• How to go passwordless with your Microsoft account
• I have a new mobile phone and I want to add it to MFA
• Cannot authenticate with E-mail when logging into Microsoft Authenticator(iOS). - Microsoft Q&A
• I have a Micrsoft business account and I am the admin and the only user registered under this account. I can't log in because i have replaced my phone and the authenticator doesn't work. - Microsoft Q&A
• Microsoft Authenticator app doesn't show 6-digit OTP code - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A