Database copy '{0}' on server '{1}' is currently a seeding source. You need to cancel the existing seed operation before ...

Database copy '{0}' on server '{1}' is currently a seeding source. You need to cancel the existing seed operation before proceeding with the move. You can also use the Move-ActiveMailboxDatabase cmdlet with the -SkipLagChecks and -MountDialOverride parameters to forcibly move the database, if needed. If the database isn't mounted after successfully running Move-ActiveMailboxDatabase, use the Mount-Database cmdlet to mount the database.