Update 11/19/2025: Customers who had the "ExchangeManagedAttributesUpdateNotAllowed" errors in their Entra Connect clients with earlier versions should now upgrade to version 2.5.190.0 where this is...
Updated Nov 19, 2025
Version 5.0
Blog Post
It appears that there is a problem in Exchange Online Powershell.
When ‘Set-Mailbox alias -IsExchangeCloudManaged $true -ErrorAcction Stop’ is used, an error occurs. The '-ErrorAcction Stop' causes the problem.
Error:ERROR updating 'alias' (email address removed for privacy reasons): System.Exception: ||Das Kontoattribut kann nicht geändert werden, da nur die Exchange-Attribute für diesen Benutzer bearbeitet werden können. Keiner der Parameter wurde geändert. Weitere Informationen finden Sie unter: https://aka.ms/ExchangeCloudManaged
When 'Set-Mailbox alias -IsExchangeCloudManaged $true' is used without ErrorAcction, it works.