Mailbox migration can take a long time to finish. Most of the time this can be a pain when there is a lot of pressure on the migration project.
To get more insights in these issue you can execute the command bellow to get an overview of what is going on with your mailbox move.
Get-MoveRequest | get-MoveRequestStatistics
(Get-MoveRequestStatistics <id> -IncludeReport).Report.TargetThrottles
As you can see in the print screen there are a lot of TotalStalledDueTo… These error occur most of the time due to an error on the back-end of the Microsoft services.
Common mailbox migration issues
Some of you might know this but Microsoft is handling a queue for moving and migrating company mailboxes and user placeholders that want to on board. This will hit most of the services of office 365 like Exchange online and Azure AD.
Microsoft is doing this to make sure everybody has the same performance and expectations to migrate, they do this so their services will not be overloaded with move requests.
There is no solution for these error messages the only thing you can do is create a ticket for Microsoft. But we have seen that most of the time the Microsoft Fasttrack team is not using the migrationbatch method or MRS replication. They are just using the individual request. The reason for that is (cause they are easier to manage)
Note: just keep raising to tickets, just to make a signal to Microsoft.
Source: Thanks Michel de Rooij and Thomas Verwer to bring this to our attention.