Can not sign into authenticator app since changing phone

Follow these steps depending on the type of account and whether there is another admin who can help.

1. If this is a work or school (Microsoft 365 business) account and there is another admin
   • Ask another cloud services admin to reset the Multi-Factor Authentication (MFA) settings for the account:
     1. The other admin signs in to the cloud service portal as admin.
     2. Goes to https://account.activedirectory.windowsazure.com/usermanagement/multifactorverification.aspx.
     3. Selects the checkbox for the affected account.
     4. Selects Manage user settings.
     5. Checks Require selected users to provide contact methods again, then selects Save.
   • After this, sign in again and reconfigure MFA (Authenticator, phone, etc.).
2. If this is a work or school account and there is no alternative sign-in method configured
   • If another verification method (such as office phone, SMS, or another device) was set up previously:
     1. Sign in as usual until prompted for verification.
     2. Use the Sign in another way option and choose the alternative method.
   • If no alternative method exists, contact the organization’s IT help desk or Microsoft 365 admin and ask them to reset MFA as described above.
3. If this is a work or school account and the user is the only admin (no other admins available)
   • Microsoft’s Data Protection team must assist with resetting the admin’s MFA.
   • Call Microsoft’s customer service using the published customer service phone numbers and request a ticket for MFA reset/Data Protection assistance for a tenant admin:
     • When the IVR asks what the problem is, answer “Authenticator” or “Lost account.”
     • When asked what product, answer “Office 365 for business.”
     • Confirm it is a company account, that the caller is the administrator, and that there are no other admins.
     • Confirm a service request is needed and ask to be routed to the Data Protection team.
   • If reaching an agent by phone is difficult, create a temporary Microsoft 365 trial tenant, sign in to its Admin Center, and open a support ticket from there, clearly stating that access is needed to a different existing tenant where the caller is the only admin. The Data Protection team can then verify identity and reset MFA on the original tenant. The trial subscription should be cancelled once the issue is resolved.
4. If the mobile device was changed but the account is still accessible via another method
   • Sign in using any available method (e.g., SMS, office phone, or existing session) and then:
     1. Go to the Additional security verification page (https://account.activedirectory.windowsazure.com/proofup.aspx?proofup=1).
     2. Remove the old phone from Security info.
     3. Use Add sign-in method to add the new phone and reconfigure Microsoft Authenticator.
5. If the phone was lost or stolen
   • Sign in using a different method if available, or ask the organization’s Help desk to clear MFA settings.
   • After settings are cleared, the next sign-in will prompt to register MFA again on the new device.
6. If repeated failed attempts have blocked sign-in
   • Microsoft Entra multifactor authentication may temporarily block sign-in after many attempts. Wait and try again later, or use another MFA method if one is configured.
   • If malicious activity is suspected, the organization’s IT admin should review Microsoft Entra sign-in logs.

If none of the above paths are available (no other admins, no alternative methods, and no access at all), the only supported path for a business account is to work with Microsoft support (via phone or via a trial tenant) and the Data Protection team to reset MFA.

References:

• Can't use Azure Multi-Factor Authentication to sign in to cloud services after you lose your phone or the phone number changes
• Use a screen reader to set up and troubleshoot multifactor authentication
• Common problems with two-step verification for a work or school account
• Troubleshoot problems with Microsoft Authenticator
• Authenticator Did Not Complete Login
• Sign in to Microsoft 365
• I cant log in to my business account because it is requiring Authenticator app which I do not have - Microsoft Q&A
• How Do I Regain Access to My Account After Losing Access to Microsoft Authenticator? (Urgent Request). - 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 sending me into a spiral - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A