Symptoms
When you try to log in to a mailbox or move a mailbox to an Exchange 2019 Database Availability Group (DAG) member server, you receive the following error message:
Note
There is no support for this operation.
You also encounter this issue if the server is recovered. This is because you have to remove the node from the cluster before you can run the server recovery process.
Resolution
To fix this issue, install Cumulative Update 13 or a later cumulative update for Exchange Server 2019.