Error Code: 500121 Request Id: 74d019d3-654f-4920-8471-ac1a9c402500 Correlation Id: 5876e453-43f9-48c8-be65-0b4907c2f79d Timestamp: 2026-10-27T18:29:01Z

Hi,

Error 500121 indicates that the MFA authentication request was not completed successfully.

Please try the following:

1. Try signing in again and make sure you approve the Microsoft Authenticator notification or enter the correct verification code.
2. If you are not receiving the notification, select Sign in another way and try another registered authentication method, if available.

Apart from the usual MFA timeout or Authenticator registration issues, there is another possibility worth checking.

Did you accidentally select "No, it's not me" or "Report suspicious activity" when receiving a Microsoft Authenticator notification?

If so, Microsoft Entra may have flagged your account as high risk, and your organization's security policies could be preventing further sign-ins.

If this is a work or school account, ask your IT administrator to:

Check Microsoft Entra ID → Monitoring & health → Sign-in logs for the exact failure reason and authentication details.

Navigate to Protection → Identity Protection → Risky users / Risk detections and check whether your account was flagged for suspicious activity.

If the sign-in was legitimate and the activity was accidentally reported, investigate and remediate the user risk appropriately.

If required, reset your MFA authentication methods and allow you to register them again.

Important note to your Admin: Simply resetting Microsoft Authenticator or issuing a Temporary Access Pass may not resolve the issue if a risk-based access restriction remains active.