Microsoft 365 Login

If the Microsoft Authenticator app on a new phone is not working and sign-in is blocked by MFA, the options depend on whether this is a work/school (Microsoft Entra / Microsoft 365 business) account and whether there is another admin.

1. Try an alternative MFA method

• On the sign-in screen, when prompted for Authenticator, look for options like “Use a different verification option” or “I can’t use my Microsoft Authenticator app right now”.
• If SMS, phone call, or another method was previously configured, select it and complete sign-in that way.
• If repeated failed attempts have occurred, Microsoft Entra MFA may temporarily block more attempts. In that case, wait and try again later or use a different MFA method if available.

2. If this is a work or school account and there is an admin

• Contact the organization’s Microsoft 365 / Entra ID administrator or Help desk and ask them to reset MFA settings.
• Admin steps (summary from guidance):
  • Go to Microsoft Entra admin center (https://entra.microsoft.com).
  • Navigate to Users → All users → [select the user] → Authentication methods.
  • Use Require re-register multifactor authentication so the user can set up MFA again on the new phone at next sign-in.

3. If this is a work or school account and the locked-out user is the only admin

• The only-admin scenario requires Microsoft’s Data Protection team to verify identity and reset MFA.
• Call Microsoft’s Customer service phone numbers - Microsoft Support and request a ticket with the Data Protection team to reset the admin’s MFA.
• When navigating the phone system, clearly state:
  • The problem is with Authenticator.
  • The product is Office 365 for business / company account.
  • The caller is the only administrator and is locked out due to MFA.
• If direct phone support is difficult to reach, one documented workaround is:
  • Create a new trial Microsoft 365 tenant (separate environment) using a business trial.
  • In the new tenant’s Microsoft 365 admin center, open Support → Help & support and submit a ticket explaining that access is needed to a different, existing tenant where the caller is the only admin and is locked out by MFA.

4. If the device was changed but the old phone is still available

• If the old phone still has a working Authenticator registration, use it once more to sign in.
• Then go to the Security info / Additional security verification page for the account and:
  • Remove the old phone/app registration.
  • Add the new phone and reconfigure Microsoft Authenticator following the “Download and install the Microsoft Authenticator app” guidance.

5. If no alternative method works and there is no admin access

• For business/work/school accounts, only the organization’s admin or Microsoft’s Data Protection team can reset MFA.
• For personal Microsoft accounts (not covered in the provided context), follow the account recovery and security options on the consumer account portal.

References:

• Use a screen reader to set up and troubleshoot multifactor authentication
• Work or school account help
• Common problems with two-step verification for a work or school account
• Microsoft Authenticator FAQs
• 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
• I need to reset my mfa methods - Microsoft Q&A
• Microsoft authenticator sending me into a spiral - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A
• Microsoft Authenticator app doesn't show 6-digit OTP code - Microsoft Q&A