Exchange 2010 – Exporting PST files – Cannot access a failed instance

While performing an PST export from a Windows SBS 2011 server I was hitting the following error:

Error: \\servername\PSTExport\user.pst –> Cannot access a failed instance

Basically the error is suggesting that the PST export process has lost ownership of the PST it was creating.  Due to this the error log is also filled with other errors which can look a bit scary, however these are purely as a result of the main error and not a cause so don’t get distracted by them.

Example errors:

26/09/2016 23:24:58 [SERVER] A corrupted item was encountered during the move operation. The item wasn’t copied to the destination mailbox.

26/09/2016 23:25:02 [SERVER] Fatal error MailboxReplicationPermanentException has occurred.

So there is a quick fix, as suggest the export process has lost connectivity to the PST file.  The causes of this can include

  • Anti virus scanning
  • Server backup processes
  • Exchange back processes

So the key here is to look at the various services that are running on your server and disable/configure them so they don’t interfere with the export processes.  The biggest culprit I’ve found is the AV scanner grabbing the PST, more of an issue when the PST files take a very long time to build because of their size.


Leave a Reply

Your email address will not be published.