Ошибка:
Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted. The same restriction applies if similar serialization is done by the custom session state store in 'Custom' mode.

Stack Trace:

[RemotingException: Remoting cannot find field __identity on type System.MarshalByRefObject.]

Что такое __identity on type System.MarshalByRefObject????