Cant access my Authenticator app

Dear @Kaitlyn James,

Thank you for reaching out and for explaining your situation in detail.

If you're using a work or school account, please note that MFA settings are typically managed by your organization's IT administrator. In this case, I recommend contacting your admin to verify your MFA configuration or reset your authentication methods.

Your administrator can follow the guidance in the following article: Manage authentication methods for Microsoft Entra multi-factor authentication

If you’re unsure who your administrator is, this article may help: How do I find my Microsoft 365 admin?

Please also note that this forum is a user-to-user support space. Forum moderators do not have access to user accounts and are unable to reset passwords, change authentication methods, or intervene in sign-in issues.

Therefore, if you are the only administrator in your organization, then you need to involve Microsoft data protection team. Please try to find the related hotline number to call the frontline let them raise a ticket for you: Customer service phone numbers - Microsoft Support 

In some countries, this is an automated conversation: First, when you call the hotline, they will ask you what kind of problem you are struggling with. 

Answer: Authenticator. 

A: What products do you use? 

B: Office 365 for business. 

Verification: Education or company account? 

B: For companies 

A: Are you an administrator? 

B: Yes. 

A: Are there any other administrators in your organization? 

B: No. 

A: I need one.... Service request? 

B: Yes 

  If your organization's Office 365 Business/Education subscription is from a partner or reseller, and the global administrator is unable to open a service request on your end, contact the reseller's support provider to help open a service request on behalf of you instead. 

If you still cannot reach to agent, there is still a workaround, you might consider registering for a new tenant by signing up for a trial subscription via this link Compare All Microsoft 365 Plans | Microsoft. This would allow you to create a new tenant following the provided prompts. Once set up, you can access the admin console of the new tenant and submit a support ticket requesting to speak with the Data Protection team on behalf of your previous tenant.  

Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.  

I understand that this entire process can feel long and complicated, and I truly appreciate your patience while working through it. These steps are in place to protect the security of your account, so I hope you can understand why they are required. I sincerely hope you’ll be able to regain access to your account soon. If you need help at any point, or if you have any questions during the process, please feel free to reach out, I’m always here and happy to assist.  

Thank you again for your understanding and patience. 

Warm regards, 

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Error code 500121 indicates that the Microsoft Authenticator (or another broker app) did not complete the authentication process.

To resolve this, use these steps:

1. Open Microsoft Authenticator (or the Company Portal/primary Microsoft app used for work sign-in) on the device and complete any pending prompt or approval.
2. Ensure the app is not locked:
   • Unlock the device and the Authenticator app.
   • If an input box or prompt is missing, unlocking the app can make it appear.
3. Check notifications:
   • Make sure notifications are enabled for Microsoft Authenticator and not set to silent.
   • Check for any SMS/text verification codes that may have arrived quietly.
4. Update and verify device settings:
   • Install the latest version of Microsoft Authenticator.
   • Confirm the device has a working internet connection (try switching between Wi‑Fi and mobile data).
   • Verify the device’s date and time are set correctly (automatic time is recommended).
5. If sign-in has been attempted many times:
   • Microsoft Entra multifactor authentication may temporarily block further attempts.
   • Wait and try again later, or use a different MFA method if one is configured.
6. If the password is forgotten or no MFA method works:
   • Use the password reset flow if available: Reset your password.
7. If access is still not possible:
   • Contact the organization’s IT administrator or Help desk and provide the error code and timestamp so they can check Microsoft Entra sign-in logs and, if needed, reset MFA methods or assist with account recovery.

If the account is a work or school account and there is no way to complete MFA, only an IT admin (or Microsoft support via the Data Protection process, if the user is the only admin) can fully restore access.

References:

• Authenticator Did Not Complete Login
• Authentication did not complete
• Troubleshoot problems with Microsoft Authenticator
• Common problems with two-step verification for a work or school account
• 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
• Cannot authenticate with E-mail when logging into Microsoft Authenticator(iOS). - 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