I migrated from 2010 to 2013 and only one mailbox fails to move. I can move it within the 2010 mailbox databases but I cannot get it to migrate to a 2013 database. The migration takes a loong time to move the 500MB mailbox and eventually will fail with an error stating the following
"This job hasn't made progress since {date / time}. I have tried to move it several times and it fails with the same error each time. All other mailboxes in the entire environment have been successful with no issues. I moved it to another 2010 mailbox database with no issues but the 2013 move failed again afterwards.
Any ideas what the issue could be?