Can not log on to specific organization in Microsoft teams with Authenticator error (500121)

Question

When I try to log on to other organization (guest), it requires MFA through MS Authenticator. (Invitation was from the other organization made successful, and was possible to log on 6 months ago.) But there is no notification pop up in Authenticator, and 6 digit OTP is not working too. Below error was identified. (Error Code: 500121 Request Id: f885503d-83ef-400d-8895-2cc12532f200 Correlation Id: 07812b11-5986-47b4-b4fb-da2a249e443a Timestamp: 2024-01-25T15:26:35Z ) Deletion and creation of my account in the organization were done by the owner several times, but didn't work. This is happening only for the other organization, while I'm able to log on my organization in teams. I contacted my company's IT support to initialize my Authenticator account, and reset the account setting, but still in same situation. Could you tell me what could be checked and modified to fix the problem?

Answer 1

Hi @Joohwan Kwon

When the other organization has enabled MFA, you need to use MS Authenticator to perform MFA when logging in to the guest account.

Users may report fraud in their authenticator requests, and once this happens, the account will be blocked.

To unblock the account, contact the guest tenant administrator Go to Microsoft Entra Admin Center - Security - Multi-Factor Authentication - Block/Unblock User. Click Unblock under the Action column for the affected user.

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