I’ve been having a problem with remote mailbox moves to Office 365. The move completes successfully and everything works ok, but it always generates the following error:

“Could not load type 'Microsoft.Exchange.MailboxReplicationService.RequestPriority'…”

I’ve seen this mentioned a few times on the Office 365 community forums and some of my colleagues are also seeing this. The good news is that after installing Update Rollup 5 for Exchange 2010 SP1 this error no longer appears.