If you get an error when you move mailboxes from on-premises to Exchange Online in a hybrid deployment one of the errors you can get is: "User is already being moved" - the technical error looks like this:
The error you get
Error: UserAlreadyBeingMigratedException: The user 'Name' already has a pending request. Mailbox 'Name' is already being moved to 'Cloud Database Name'.
Error: MigrationPermanentException: The onboarding move could not be created because user 'Name' is already being moved. --> The onboarding move could not be created because user 'Name' is already being moved.
This issue may occur if one of the following conditions is true:
- Mailbox 'Name' is already being moved to '<Cloud Database Name>'.
- You already have a move request (active or orphaned) in on-premises Exchange Server for that user. In this scenario, the error message is most likely as follows:
- The onboarding move could not be created because user 'Name' is already being moved.
How to fix the error and get the mailbox synced
Open Active Directory Users and Computers in Domain Controller (DC) server.
Locate the affected user, click View, select the Advanced Features check box, and then open the Attribute Editor tab.
Look for msExchMailboxMove attributes, and check whether any value is set for that user, if there is not a migration running them double click the value and choose "clear"
You may also need to check the other attributes to ensure they are clear as well:
msExchMailMoveStatus
msExchMailboxMoveSourceMDBLink
msExchMailboxMoveTargetMDBLink
msExchMailboxMoveSourceArchiveMDBLink
msExchMailboxMoveTargetArchiveMDBLink
Manually clear the value in Active Directory, and then create another move request in Exchange Online for that user.