You run Exchange Server 2010 and Exchange Server 2013 in a coexistence organization. When you use Outlook Web App (OWA) web parts to access a delegated calendar, you can't access to the calendar, and you receive the following error message:
"The Custom error module does not recognize this error "The Custom error module does not recognize this error".
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 3107205 - Last Review: Dec 15, 2015 - Revision: 1
Exchange Server 2013 Service Pack 1, Exchange Server 2013 Enterprise, Exchange Server 2013 Standard Edition