Session state might be invalid or corrupted Error Options

Hi,
I have a Web Farm scenario in my application where i am storing the
custom User Object in Session and all the session state

information is stored in Oracle Database .My Session Handler class
inherits from SessionStateStoreProviderBase class.


Structure of User Object is follows


User Contains Object of Generic List of Type Role Object


Role Object contains Generic List of Type Permission Object


Here is complete stack trace of exception


System.Web.HttpException: The session state information is invalid and
might be corrupted. at
System.Web.SessionState.SessionStateItemCollection.Deserialize(BinaryReader
reader) at SessionStateProviderManager.deserialize(HttpContext
p_context, String p_serializedItems, Int32 p_timeout)


Does any one has idea on this error 'Session state information is
invalid and might be corrupted' ?.


that under which scenario do we get this error and what are possible
remedies