Microsoft Authenticator App -

It sounds like you're experiencing issues with your Multi-Factor Authentication (MFA) setup after the authenticator app was reset. Since you cannot log in and are receiving an error code 500121, here are some steps you can take to resolve the issue:

1. Contact Support: Since you are the admin and cannot log in, you may need to contact Microsoft support directly for assistance. They can help reset your MFA settings.
2. Use Microsoft Graph: If you have access to Microsoft Graph, you can delete the existing authenticator apps associated with your account. This may allow you to set up MFA again. You can find guidance on how to do this in the Microsoft documentation.
3. Check for Admin Access: If you have another admin account, you could use it to manage the MFA settings for your primary account.
4. Reset MFA: If you have deleted the authenticator app, you will need to request a reset of MFA for your account through Microsoft support.

Make sure to keep your account recovery options updated to avoid similar issues in the future.

References:

• Can't set up MFA because five devices are already registered to use an authenticator app
• Microsoft Curate - Troubleshoot Multi-Factor Authentication (MFA)

Hi @Darren Butcher,

Welcome to the Microsoft Q&A forum.

Thank you for reaching out to us. I would like to provide you with the following information: Since you are the only administrator of the tenant, in this case you will need to contact Microsoft’s Data Protection team to request MFA reset support for your account.

To contact the Data Protection team, please follow these steps:

Please use the following link to make a call:https://support.microsoft.com/en-us/topic/customer-service-phone-numbers-c0389ade-5640-e588-8b0e-28de8afeb3f2#ID0EBBD=signinorgid

Instructions for the call:

• Reason for the call: AdminCenter
• Role: Global Administrator
• Request Description: Mention the keyword “AdminCenter”
• If asked whether there is another admin: Answer “No” so that you can be routed to the support team and have a service request created.

Note: We kindly ask for your understanding regarding the support scope in this forum. As moderators, we can only provide general guidance and basic troubleshooting assistance. We do not have access to internal systems or administrative tools required to handle issues directly related to accounts or backend systems. However, we will always do our best to support you within our responsibilities.

I hope this information is helpful. Please follow the steps above and let me know if it works for you. If not, we can continue working together to resolve this issue.

Thank you for your patience and understanding. If you have any questions or need further assistance, please feel free to leave a comment on this post so I can continue to support you.

Looking forward to your response.

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