Unable to change the Coexistence mode from Islands to Teams Only

Microsoft Teams

If you have upgraded your Skype for Business users to Teams and want to update the Teams co-existence mode to “Teams Only” so that users can only use Teams but still join meetings hosted in Skype for Business.

To change the coexistence mode. Open Teams Admin Portal -> Org-wide settings -> Teams upgrade

Coexistence mode from Islands to Teams Only

Change the co-existence mode to “Teams only”. You may get below error as we see in the below screenshot. There is not much information on this portal to troubleshoot this issue. However, we will try using powershell to set the co-existence mode to “Teams only” mode to see if we get more information on the console.

Also Read: External Users / Guests are able to bypass lobby – Microsoft Teams meeting

Coexistence mode from Islands to Teams Only

Using Powershell command provides more information about the issue:

Grant-CsTeamsupgradePolicy -PolicyName UpgradeToTeams
Grant-CsTeamsupgradePolicy -PolicyName UpgradeToTeams

To check if any one is set to Skype for Business only, you should check using below command and make sure no one is set to Skype for Business only mode.

Get-CsOnlineUser | FT userprincipalname,TeamsUpgradeEffectiveMode

To Fix this issue, Create below two highlighted CNAME records in your Public DNS Management Console. Try again after few hours.

DNS Records:

Microsoft Teams CNAME DNS Records

Example:

Microsoft Teams CNAME DNS Records

Now, we should be able to change the Coexistence mode to “Teams Only”.

Coexistence mode from Islands to Teams Only

External References:

Install Teams Powershell module

Set your coexistence and upgrade settings

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