ASP.NET 2.0: Why can my class access the Session object when run on my local machine, but not when I deploy it to the server?

I have a custom MembershipProvider that I'm using in an ASP.NET 2.0 application. Inside of the class that extends membership provider, I have a function called AttemptLogin() that sets session variables if the user is valid. Inside that function, are开发者_运维技巧 a number of session variable assignments similar to the following:

HttpContext.Current.Session["id"] = "12345";

AttemptLogin() is being called by the Application_BeginRequest function in global.asax. This code works fine when I open it in visual studio, and then run it in the built-in development server by clicking "Start Debugging". However, when I deploy it to our testing server (Windows 2003 Server 64-bit running IIS in 32-bit mode), execution breaks when it reaches the code above, giving me the following message:

[NullReferenceException: Object reference not set to an instance of an object.]
   CustomMembershipProvider.AttemptLogin() in c:\Inetpub\wwwroot\Josh\App_Code\CustomMembershipProvider.cs:1097
   ASP.global_asax.Application_BeginRequest(Object sender, EventArgs e) in c:\Inetpub\wwwroot\Josh\Global.asax:14
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +68
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

How can I access the session state successfully in this situation? Why does it work locally and not on the server?

Session Variables aren't available at Application_BeginRequest you should look later in the pipeline by handling the Application_AcquireRequestState in your global.asax, I'm honestly puzzled why you don't get a null ref on your dev box.

Check the web.config file on the server and make sure sessionState mode is enabled

<sessionState mode="InProc" />