User is never receiving Authentication code for login with MFA; Can't set up Authenticator app.

Question

A user in our company has been unable to receive texts to any number to authenticate her logins with MFA.

We have tried:

• Changing her phone number to a new number using Azure/Entra. No text received.
• Adding the Authenticator App. Can't set up as login is required.
• Re-requiring MFA Phone setup, Can not update the number and no text is sent.
• Some days and trying all steps again. No change.

The only indicator of the issue is this error:

With this error code:

Error Code: 500121

Does anyone have any idea of how to fix this? I saw some people with 'Invalid region codes' but we have not had this with any other users in our company and we are all New Zealand based.

Answer 1

Hello @SamQuilter-6929 and thanks for sharing your solution. Since accepting and rating your own answer is not possible I'm reposting it here so you can accept and rate it so that others facing a similar issue can easily find a solution.

We eventually found that the user was blocked in our MFA settings. We solved this by following these actions: Go to Microsoft Azure/Entra Active Directory Users and Groups. Click Security. Click Multifactor Authentication. Check the Blocked Users, if user is listed in that location, unblock them and try logging into their account again.

Answer 2

The simplest solution may be to reset the account so a new QR code can be generated with which user can relink the authentication device to the account.

--please don't forget to close up the thread here by marking answer if the reply is helpful--