MS Authenticator Error Accessing Client Team's site

Question

I haver a user who is unable to join/access a clients Teams site. They have MFA enabled, and he is using the MS Authenticator app. However, when he gets a verification code form the Authenticator app, he gets an error:

You didn't enter the expected verification code Please try again. Error Code: 500121.

W have Office 365 but do NOT have MFA enabled.

We have had the client delete and recreate my users account. He has deleted and reinstalled MS Authenticator on his cell. Neither of these has solved the issue. We have two other users who have successfully joined that client's Team's site, so it's something with this user.

Any help would be greatly appreciated.

Answer 1

Hi Michael. If the user can't use other device, you need to discover what is the difference in the devices without problem to access and the device that can't do it.

Is all devices updated (operative systems, apps, etc)?

Greetings and have a nice day.

Answer 2

Hi Sergio,

Thanks for getting back to me.

1. Can the user try using other device? What happen?
   Unfortunately, the user only has one phone, which has the MS Authenticator app installed.
2. Are all the guests the same account domain?
   Yes. But we do not have MFA enabled on our system

Answer 3

Hi Michael, I'm Sergio, it's a pleasure to help you.

I'm really sorry the situation.

You need to isolate the problem causes, please answer me:

1. Can the user try using other device? What happen?
2. Are all the guests the same account domain?

Greetings.