A popular migration mode for organization with an on-premises deployment of Microsoft Exchange Server is to use remote move migration. During a migration, regardless of the migration mode, there can be issues that prevents a migration batch from succeeding. This post is about one of those issues which a customer of mine brought to me a few days back.
In this incident, the administer who was migrating users had created a migration batch with a single user. After few seconds creating the batch, he had received an email similar to below.
According to the above email, the migration batch has completed, but zero mailboxes were migrated. The administrator has checked the migration status from Exchange Online Admin Center and nothing helpful was found. Exchange Admin Center is known to be less helpful with troubleshooting migration issues. As usual, we have to turn to PowerShell for help. I connected to Exchange Online using PowerShell and ran below command.
Get-MigrationBatch -Identity "Migration Batch Name" | fl
Once I ran the command, I received an output similar to below.
As you can see the above screenshot, ValidationWarnings (within the red box) provides a descriptive message on why the batch was failed. In this particular incident, the failed user is already in another migration batch Once removed from the old batch and started the migration, user migrated successfully.