The Session object is null in ASP.NET MVC 4 webapplication once deployed to IIS 7 (W 2008 R2)

asp.net-mvc-4, iis-7

Solution

I found the solution. You have to add and remove the SessionStateModule:

  <configuration>
  ...
  <system.webServer>
    ...
    <modules>
      <remove name="Session" />
      <add name="Session" type="System.Web.SessionState.SessionStateModule"/>
      ...
    </modules>
  </system.webServer>
</configuration>

I have no idea why Microsoft doesn't add this to the web.config of the project template?

Problem

I developed an ASP.NET MVC 4 web application (.net 4.5) which runs fine in Visual Studio 2012. After deployment to IIS 7 on Windows Server 2008 R2, it seems like the HttpContext.Session object inside my controller is null. I created a simple test ASP.NET MVC 4 application to demonstrate the issue. In my test app I have a simple Home Controller ``` public class HomeController : Controller { public ActionResult Index() { if ( HttpContext != null && HttpContext.Session != null ) { HttpContext.Session[ "test" ] = "a string in session state"; ViewBag.Info = HttpContext.Session[ "test" ]; return View(); } else { if ( HttpContext == null ) { ViewBag.Info = "beeeeuuuuu - HttpContext = null!!!"; } else if ( HttpContext.Session == null ) { ViewBag.Info = "beeeeuuuuu - Session = null!!!"; } return View(); } } } ``` My Index.chtml view lookes something like this: ``` @{ ViewBag.Title = "Index"; } <h2>Index</h2> This is a simple test <p>@ViewBag.Info</p> ``` So when I run the application I get what I was expecting: ``` Index This is a simple test a string in session state ``` But after I deploy the application to the web server the website gives me the following page indicating that the Session object is null: ``` Index This is a simple test beeeeuuuuu - Session = null!!! ``` The web application is deployed to the default website which runs under the ASP.NET v4.0 application pool (integrated pipeline). I already reïnstalled ASP.NET on the server using aspnet_regiis -ir but this didn't help. The Session state is enabled (In Proc) at the ISS server. I hope anyone can help me out here cause I'm trying to solve this for quite some time. Much thanks in advance and kind regards. UPDATE: I also tested an ASP.NET MVC 4 build with .NET 4.0 instead of 4.5 and that has the same problem. I also deployed an ASP.NET Web Pages app (.NET 4.0) and that works fine (The HttpContext.Current.Session is not null in the code behind). UPDATE II: I also tried to store the Session State in a database, which worked fine on my development machine but had the same problem on the production server (HttpContext.Session still returns null).

Original source