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Microsoft Authenticator Issue – Error Code 500121

Anonymous
2025-04-15T18:38:56+00:00

Hello,

I’m hoping someone can assist me, as I’ve been stuck in an endless loop trying to access my Microsoft 365 apps for the past few days, and it’s getting really frustrating.

I recently got a new phone and had to set up Microsoft Authenticator again for my school account (which uses a SWITCH edu-ID login). I removed the account from my old phone beforehand and reconfigured MFA through the official login portal using a QR code.

Now when I try to log into any app like Outlook or Teams, I’m directed to the Authenticator app where I’m asked to verify with a code. However:

  • The number match prompt does not show up.
  • When I tap “Get Codes” and enter the 6-digit code, I get the message:
    “You did not enter the expected code.”
  • The error code shown is: 500121.

Here’s what I’ve already tried (with no success):

  • Removed and reinstalled the Authenticator app
  • Reset MFA from my account login portal and scanned the QR code again
  • Double-checked time settings to ensure automatic time and notifications is enabled
  • Made sure all apps and device software are up to date

I’m currently locked out of important services I need for school, and would really appreciate help resolving this. If needed, I’m open to fully resetting the MFA settings for my account so I can start from scratch.

Thank you in advance for your time and support.

Best regards

Microsoft 365 and Office | OneDrive | For education | iOS

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  1. Anonymous
    2025-04-18T21:00:33+00:00

    Hello.

    I'm back with you.

    Please let me know if you were able to reach out your IT support team.

    Jose R.
    Microsoft Community Support
    Support Hours: Monday to Friday 7:30–17:30 EST (Except US Public Holidays)
    Estimated Response Time: Within 1 Business Day.

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  2. Anonymous
    2025-04-16T20:19:12+00:00

    Hi.

    I understand the frustration you're experiencing. Error code 500121 in Microsoft Authenticator usually indicates a mismatch between the time settings on your device and the server. To resolve this issue, please ensure that the time and date settings on your new phone are set to automatic. This should sync the time accurately and resolve the mismatch causing the error.

    If the issue persists after adjusting the time settings, you may need to contact your school's IT support team to assist with resetting your MFA settings for your account. They can help you start the setup process from scratch to regain access to your Microsoft 365 apps.

    I hope this information helps you resolve the issue. Let me know if you need further assistance.

    Jose R.
    Microsoft Community Support
    Support Hours: Monday to Friday 7:30–17:30 EST (Except US Public Holidays)
    Estimated Response Time: Within 1 Business Day.

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