Error when doing export-mailbox and import-mailbox in Exchange Server 2010

I just got a question from a customer that was trying to import a number of pst files to to Exchange 2010. This is the error message they received:

Error:
Error was found for user@domain.com because: Error occurred in the step: Approving object. An unknown error
has occurred., error code: -2147221219
    + CategoryInfo          : InvalidOperation: (0:Int32) [Import-Mailbox], RecipientTaskException
    + FullyQualifiedErrorId : CFFD629B,Microsoft.Exchange.Management.RecipientTasks.ImportMailbox

There is a known bug in Exchange 2010 that causes export-mailbox and import-mailbox commands to fail on an Exchange Server that has both the CAS and Mailbox role installed.

To solve this you can either do the import/export via Outlook or install a separate Exchange 2010 server. Make sure that you only install the Mailbox role together with Outlook 2010 64-bit on this server.

When you are done, or the bug is fixed, you can uninstall the temporary import/export server using add/remove programs. This will remove Exchange from the server as well as remove all information regarding the server in Active Directory.

According to Microsoft Support this issue is expected to be fixed in update rollup 5 of Exchange 2010 server. I have also seen posts about a fix in Service Pack 1 so time will tell… Good luck and please don’t hesitate to let me know if you run in to any other issues.