Intermitent O365 sync error - shell was not found

Your Sync has run run successfully on previous occasions. Later, a follow up Sync fails with this error.

Processing data for a remote command failed with the following error message:

[ClientAccessServer=Server1,BackEndServer=Server2,RequestId=<>,TimeStamp=4/8/2014 3:42:44 PM] [FailureCategory=WSMan-InvalidShellID] The request for the Windows Remote Shell with ShellId <> failed because the shell was not found on the server. Possible causes are: the specified ShellId is incorrect or the shell no longer exists on the server. Provide the correct ShellId or create a new shell and retry the operation. For more information, see the about_Remote_Troubleshooting Help topic.

Microsoft has identified the cause for this error. Refer to this Microsoft Support KB article (https://support.microsoft.com/en-us3090768) for more information.

In the case of your UnitySync connection, first try to re-run the Sync to see if the problem reoccurs. If you see the error again, please contact your AD/O365 administrators.