When you proxy Exchange Control Panel (ECP) from Microsoft Exchange Server 2013 to Exchange Server 2010 Service Pack 3 (SP3) or an earlier service pack, the MSExchangeECPAppPool application pool crashes and generates a System.NullReferenceException exception.
Note This issue does not occur in Update Rollup 1 for Exchange Server 2010 SP3 or a later update.
Additionally, the following events are logged in the Application log in Event Viewer:
Note This issue does not occur in Update Rollup 1 for Exchange Server 2010 SP3 or a later update.
Additionally, the following events are logged in the Application log in Event Viewer: