i cannot sign in Azure portal.I am getting MFA issue as Error Code: 500121

@Gokulraj Nagarajan
Thank you for your post!

Error Code: 500121
This typically occurs when authentication failed as part of the multi-factor authentication (MFA) request, it may indicate a configuration or service error. To resolve this issue, can you try resetting (require re-register) MFA for your user.

Related issue - https://github.com/MicrosoftDocs/azure-docs/issues/23238

If you have any other questions, please let me know.
Thank you for your time and patience throughout this issue.

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Is possible that you miss-clicked in Microsoft Authenticator app and blocked yourself like my user bellow. I would check there first before making a ton other changes like I did 😁.

Hope this helps.

I found the solution!

When a user clicked "block" when they suspect an unauthorized sign-in attempt on the Authenticator, they will not be able to get past the MFA anymore when they try to sign in. And, of course, they will call you, the IT Administrator.

To solve this problem, you will need to unblock their account by going to:

Entra Admin Center > Protection > Multifactor authentication > Block/unblock users