Mailbox migration failed after cannot open 'System Attendant Mailbox Error' in Exchange 2013

If you have ever migrated mailboxes on Exchange 2013, you had surely come across this error when you try to move a mailbox and move request fails immediately with the error message-

"Cannot open mailbox /o=Test Lab/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=MY2013Server/cn=Microsoft System Attendant"

Well, this error occurs if the System Attendant Mailbox service is currently not accessible. But this is not server side error; actually Microsoft has done few architectural changes in Exchange 2010 by removing System Attendant Mailbox from the first database when you install Exchange 2010 Server. However, directory object still exist in configuration partition. And same changes also have been applied on Exchange 2013. 

But for Exchange Server 2013, the new architecture now depends on new arbitration mailbox for mailbox move-

“Migration.8f3e7716-2011-43e4-96b1-aba62d229136”

Now, there may be two scenarios for the errors; either the first database mailbox is dismounted, or the migration mailbox is hosted in an offline database which is no more available due to a server crash.

Here I take the first scenario. If the first database is dismounted and the error occurs with Event ID 1006, try the below fixed-

As we know now there is no System Attendant Mailbox pointing to any database, so you can rename the default database for administrative purpose. There is no risk or data loss by renaming it, but of course having offline database may causes several issues. But make sure you have kept a note of what role the database is holding before renaming the default database name.

So if you have renamed the default database, you can go head ahead and mount the store. Now you can easily move mailbox in Exchange 2013 without any error or warning.

Now I take the second scenario where mailbox is stored on an offline database which is not available because server has been crashed. To resolve this, I have done some homework and created two powershell command for moving mailboxes. But before executing the shell commands, do the following-

Firstly, you need to recreate the mailbox again. To do this, you need to deleted AD object and run Setup.exe/PrepareAD. By executing the procedure, it will recreate AD object.

Once the AD account is created, you can run below commands to configure a mailbox for the account (or, mailbox enable the new AD object)-

Enable-Mailbox -Arbitration -Identity "Migration.8f3e7716-2011-43e4-96b1-aba62d229136"

AND

Set-Mailbox "Migration.8f3e7716-2011-43e4-96b1-aba62d229136" -Arbitration –Management:$true

That’s it. These are two simple solutions to resolve this error. 

So follow the steps, and try again to move the mailbox. I believe you have done now!