[Error Code] 0x8004060c [Explanation] 
The migration tool attempted to update a message in Google Apps but failed. Typically, this occurs when the system is trying to migrate mail that has already been migrated. This error is not fatal, as the mail has already been migrated and this error just indicates that it has already been moved. If you decide to run against the same user again, the impact of this is that bandwidth will be wasted as we try to reimport existing messages (which we will not allow).