Losing session data in ASP.NET

Question

I moved an ASP.NET site running on a server with .NET 1.1 to another server running with .NET 2.0.

In one of the pages I have the following code to detect an expired session:

  protected void Page_Init(object sender, System.EventArgs e) {  

    if ( Session["XBCPEmail"] == null ) {
      Response.Redirect("signin.aspx?expired=yes");
      return;
    }
  }

(Session["XBCPEmail"] == null) is resolving as true (as if the session had expired) in one unexpected case, after clicking one of the buttons of the page. It happens with only one of the buttons. Just like other buttons in the same page, the button event handler ends with this code redirecting to the same page:

Response.Redirect("cpanel.aspx"); 

I checked and at the time of Response.Redirect("cpanel.aspx"); the value of (string)Session["XBCPEmail"] is a valid string, so I'm not sure what can happen between the Response.Redirect and the Page_Init that could be making the Session["XBCPEmail"] become null.

Which could make a Session variable in .NET 2.0 become null? This code does not have that issue in 1.1 and, even in 2.0, it only affects one button on the page.

UPDATE: The issue only occurs if the button event handler calls an external .exe program, with the code below. If this code is commented out, the Session variable is not null. How can the creation of an external process to run a command line program have any impact on if a Session variable is null or not?

private string CallBridge3(string task, string arg1, string arg2, string arg3) {

    Process process = new Process();

    process.StartInfo.FileName = MapPath("bridgefcp.exe");
    process.StartInfo.Arguments = "-" + task + " \"" + arg1 + "\" \"" + arg2 + "\" \"" + arg3 + "\"";
    process.StartInfo.RedirectStandardOutput = true;
    process.StartInfo.UseShellExecute = false;

    process.Start();

    string output = process.StandardOutput.ReadToEnd();
    process.WaitForExit();
    return output;
  }  

UPDATE 2: The problem has vanished after installing .NET 4.5 on the Windows 2008 R2 with IIS 7.5 machine, instead of using the one that came by default, which was .NET 2.0.

Answer 1

You need to update web.config as mention below :

<httpCookies requireSSL="false" />

Answer 2

For MVC, make sure the web.config has below configuration.

<httpCookies httpOnlyCookies="true" requireSSL="false" />

in <system.web> section

Answer 3

I encountered this problem when setting the Session variable before a redirect. I had enableSessionState="ReadOnly" in Web.config. It happens because the session does not exists and the redirect happens before the client can set the session cookie.

My solution was to set a dummy Session variable in the previous page load (login page in my case).

protected void Page_Load(object sender, EventArgs e)
{
    // Put this in master page or login page
    Session["createSession"] = true; /* ensure there's a cookie for session */
}