A couple of days ago I was working with a client to move hidden mailboxes into a new database. I ran the command to move the mailboxes and I got an error stating that the mailbox had already been moved.
This error happens when you try to move a mailbox that has already been moved. You need to go back to the new Exchange 2016 server.
If you use the command.:
You will see the complete list of the move request(s).
The following command can be used to complete the request.
[PS] C:\Windows\system32>Get-MoveRequest -movestatus completed | remove-moverequest
Are you sure you want to perform this action?
Removing completed move request “Administrator”.
[Y] Yes [A] Yes to All [N] No [L] No to All [?] Help (default is “Y”): A
After you select “A”, all completed move request will be deleted.