Issue
At the end of Microsoft Teams migration – Skype for Business decommissioning process, we were trying to set up the global TeamsUpgradePolicy to “TeamsOnly”, we got this error “This organization cannot be upgraded to TeamsOnly at the Tennant level because this is an on-premise deployment of Skype for Business detected in 1 or more of it sip domains…”
Screenshot
Troubleshooting
After reviewing the current Skype for Business topology and checking against Skype for Business to Teams progress and cannot find anything useful, the domain listed is the correct alternative domain published. After some more digging, found the issue is caused by an incorrect DNS name.
What happened before is there are 2 domain names configured in Skype for Business topology initially, the first one is the active one in use the other one is added in the topology but has never been actively used since the business acquisition, the public DNS records are never added for this secondary domain.
Solution
Since this customer’s domain is registered at Godaddy, the fix is straightforward, add the Skype for Business/Teams needed public DNS record in and run the Powershell again. the issue is fixed.
Related link
Disable your hybrid configuration to complete migration to Teams Only
https://docs.microsoft.com/en-us/skypeforbusiness/hybrid/cloud-consolidation-disabling-hybrid
Error when switching a tenant to Teams Only mode
External Domain Name System records for Office 365