Exchange Backup Failure

We have a Backup Exec 2012 server (Version 14.0 Rev 1798) that every few days will fail on the exchange backup with the following error:

Error category    : Resource Errors

Error             : e000846b - The resource could not be backed up because an error occurred while connecting to the Agent for Windows. The correct version of the Agent for Windows must be running on the target computer.

For additional information regarding this error refer to link V-79-57344-33899

this never happens near the beginning, always near the end of the backup. I made sure everything was updated, updated the agent on the Exchange server and even broke the job apart from the verify just to make sure that was not the reason for the failure.