If you get the following error: Unable to serialize the session state error.

Look at the stack trace.

[SerializationException: Type 'ReportCustomeAdHocConfig' in Assembly 'App_Code.zrve4rl0, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable.]

Make it (in this example 'ReportCustomeAdHocConfig') serializable by the example shown below: VB

Public Class VBLesson
    Public LessonTitle As String
    Public LessonNumber As Int16
End Class