Authenticator problems

Question

Hi, I have a problem with my authenticator. I got a new phone and apps were transferred to it. However, I undone my mobile purchase and went back to my old phone. Now my authenticator doesn't work on my old phone anymore. I've tried restarting the phone. Redownloading the app etc. but nothing works. I think my account needs to be reset somehow.

Answer 1

Because the phone change broke the link between the Microsoft Authenticator app and the account, the sign-in methods need to be reset and set up again; just reinstalling the app on the old phone is not enough.

Use the appropriate path based on the type of account:

1. If this is a work or school (Microsoft 365 business/education) account and there is another admin
   • Ask an administrator to reset MFA:
     • Go to Microsoft Entra admin center → Users → All users → select the user → Authentication methods → Require re-register multifactor authentication.
     • After this, sign in again and set up Microsoft Authenticator from scratch on the old phone.
2. If this is a work or school account and there is no other admin (you are the only global admin)
   • A standard reset is not possible from the portal; Microsoft’s Data Protection team must unlock the tenant:
     • Call the regional support number from Customer service phone numbers - Microsoft Support and clearly state:
       • The issue is with Microsoft Authenticator / MFA.
       • The product is Office 365 for business / Microsoft 365.
       • It is a company account.
       • You are the only administrator and are locked out by MFA.
     • Ask them to open a service request and route it to the Data Protection team to reset the admin’s authentication methods.
   • If direct phone support cannot be reached, create a temporary trial tenant (Microsoft 365 trial), go to its admin center, and open a support ticket from there requesting Data Protection help for the original tenant, as described in the context.
3. If this is a personal Microsoft account (Outlook.com, Hotmail, etc.)
   • Use any available alternative verification method (SMS, email, etc.) on the sign-in page to get back in and then remove/re-add the Authenticator method in the Security info / account security settings.
   • If no alternative method works and access is completely blocked, follow the account recovery and password reset flow starting from the sign-in page and use the “I don’t have any of these”/similar options to recover the account, then reconfigure Authenticator once access is restored.

Once access is regained and MFA is reset, configure the old phone as the active device for Microsoft Authenticator and remove any unused/old devices from the account’s security/MFA settings so future prompts do not go to a different phone.

---

References:

• Troubleshoot problems with Microsoft Authenticator
• Use a screen reader to set up and troubleshoot multifactor authentication
• 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 sending me into a spiral - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A
• Severity A Situation - Locked out of global admin account (MFA) - business down - Microsoft Q&A
• Microsoft Authenticator FAQs

Answer 2

Whats the phone number to Customer service phone numbers - Microsoft Support