Guest accounts from one company unable to sign-in

PT Maliborski 246 Reputation points

Hi All,

For few years now every guest account in our tenant was signing in using their company email address.

Two days ago something changed and guest users from one company, when trying to sign in to our tenant, get error that "Selected account doesn't exist in tenant". Well, it does exist!

I have reset Redemption status, eventually I have fully removed and re-invited user - still the same message.

Users from other companies can still log in with no issues - just one company is affected.

I've opened case with Microsoft and was told that "Guest users should use tenant UPN in format of".

I said "What the hell? Never had to do anything like that. This kind of UPN is difficult to re-type, crazy hard to remember".

I have passed this MS response over to the affected guests to try and still waiting for feedback, but can't imagine this is the solution.

Maybe someone has seen something like this?

Microsoft Entra ID
Microsoft Entra ID
A Microsoft Entra identity service that provides identity management and access control capabilities. Replaces Azure Active Directory.
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