Global.asax Error handling: Quirks of server.transfer

Question

Hi,

In my global.asax, I am checking for a 404, and transferring to the 404 error page as per the below:

    If HTTPExceptionInstance.GetHttpCode = 404 Then

        Server.ClearError()

        Response.TrySkipIisCustomErrors = True
        Response.Status = "404 Not Found"

        Server.Transfer("~/Invalid-Page.aspx")

    End If

The problem is, my Invalid-page.aspx uses some session code (Session("somevariable")), which throws an exception "Session state can only be used when enableSessionState is set to true, either in a configuration file or in the Page directive. " because I am using a server.transfer (I believe this is a known issue?).

If I use a Response.Redirect, there is no problem. However, this would mean that the header of the error page is a 200, not a 404.

What would be the best workaround for this?

Answer 1

Check if EnableSessionState is set to true in the page directive of Invalid.aspx

<%@ Page enableSessionState = "true" .... %>

Answer 2

Weird! Server.TransferRequest does exactly what I want without losing the session state!