Guest access to Teams in another Tenant after Tenant-to-Tenant migration - not working

[Thomas Friis Poulsen]

We have migrated a domain to a new Tenant. Users have same UPN in the new Tenant as before.

Some of our users are also Teamsguest in other Tenants - but after the migration they cannot login anymore. We have tried to get new invites from the external Teams but without any luck. 

We see the Tenant selection in Teams and can select the external Tenant but it just returns to our own Tenant.

Any thoughts on this?

-Thomas

[#2 · Accepted solution]

@Thomas Friis Poulsen have you tried deleting and inviting the user again and then following a “tenant specific” link to the external Team in the browser (copy a link to the Team, send it to the user and ask them to cancel the “open in Teams” option and open in the browser instead). The user should get the OAuth tenant acceptance form again because you have deleted the original guest (with its Accepted Invitation UserState).

This often fixes Teams switching issues.

Then log off the Teams client and login again to see the updated tenant from the browser in Teams. 

P.S. If you don’t want to lose the group memberships in the external tenant you can create a script to save all the groups and applications from the old guest user and add them to the new guest user.