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Cannot use my authenticator app

Sean Molloy 0 Reputation points
2026-04-09T11:15:59.05+00:00

I have been trying to get resolution on my Microsoft 365 and authenticator app issue and pretty frustrating. I recently upgraded my Microsoft 365 and it reverted to the email address from a long time ago [Moderator note: personal info removed]@gmail.com. My email should be [Moderator note: personal info removed]@millstreetcoachingconsulting.com. I cannot access my teams / outlook at times across my devices as I cannot use the authenticator app and it sends me in a loop between 365 and authenticator. I was with someone from the support desk and we completely cleaned out all older files / profiles and libraries but I still cannot log in to authenticator using the [Moderator note: personal info removed]@millstreetcoachingconsulting.com profile to validate my identity and use the apps on the move.

Can you help me please.

Sean

Microsoft 365 and Office | Subscription, account, billing | Other | Other
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  1. Jess-Q 9,585 Reputation points Microsoft External Staff Moderator
    2026-04-09T12:31:39.79+00:00

    Hi @Sean Molloy ,

    Please understand that our forum is a public platform, and we will modify your question to cover your personal information including your organization domain name in the description. Please notice to hide these personal or organization information next time you post error or some information to protect personal data.    

    I have moved the information to the Private message if you need to add any more privacy information please add it in there.

    User's image

    Regarding your issue, this is caused by an MFA configuration problem on the tenant side. Please contact your IT administrator and ask them to revoke your MFA sessions and remove all existing authentication methods for your account in Microsoft Entra ID, then re‑register MFA.

    They can follow these steps:   

    1. Sign in to the entra.microsoft.com as at least Authentication Administrator.   
    2. Select User -> All user.   Select the user (your account) to act on and select Authentication methods. then select Require re-register of multi-factor authentication.    
    • Require re-register MFA: This disables all previous authentication methods. You'll then be prompted to configure a new MFA authentication method the next time you try to sign in, so you can set up from the start and add a new authenticator app.   

     User's image

    For more details, please refer to: Manage user authentication methods for Microsoft Entra multifactor authentication. 

    Note: Once re-registration is triggered, all your existing MFA methods such as phone numbers, Authenticator app, or other verification options will be removed. You will need to set up new MFA methods during your next login. Please ensure you have access to a valid phone number or the Microsoft Authenticator app before attempting to sign in again. 

    Hopefully it will help work with your issue and if you have any other questions or need further assistance, feel free to ask.   

    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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