Invalid tenant identifier error in MACP M365 after installing CU1

Symptoms

When you sign in to Microsoft 365, you receive the following error message:

Note

Specified tenant identifier 'undefined' is neither a valid DNS name, nor a valid external domain.

Resolution

To fix this issue, install the following hotfix update:

Workaround

To work around this issue, run the updated Setup-AzureAdForSFBControlPanel.ps1 script after applying the CU1 update when configuring Microsoft 365 authentication with MACP.

For more information, see Skype for Business Server 2019 control panel authentication script.