We're running a 2007/2013 Hybrid and have successfully migrated several accounts to Exchange Online which are working without issue.
I do however have one account I just cant get migrated and it fails with the following report. I don't think either of the reasons listed are relevant. I am the only admin, the mailbox isn't locked, and lastly MRS must have the correct permissions as I've migrated mailboxes successfully before and after this one.
If I check the current status of the job while its migrating it only ever syncs 468kb of mailbox data and then gets stuck
I've managed to migrate the mailbox from its original DB to another DB on the 2007 server so there is nothing fundamentally wrong with the mailbox itself.
Has anyone else ever encountered this error ?
Thanks
"Error: Couldn't switch the mailbox into Sync Source mode.
This could be because of one of the following reasons:
Another administrator is currently moving the mailbox.
The mailbox is locked.
The Microsoft Exchange Mailbox Replication service (MRS) doesn't have the correct permissions.
Network errors are preventing MRS from cleanly closing its session with the Mailbox server. If this is the case, MRS may continue to encounter this error for up to 2 hours - this duration is controlled by the TCP KeepAlive settings on the Mailbox
server.
Wait for the mailbox to be released before attempting to move this mailbox again."