Redirecting to another page on Session_end event

Question

I would like to auto-redirect to login page when session time outs.

In web.config file, i have the following code

Answer 1

Session_End is called when the session ends - normally 20 minutes after the last request (for example if browser is inactive or closed).
Since there is no request there is also no response.

I would recommend to do redirection in Application_AcquireRequestState if there is no active session. Remember to avoid loops by checking current url.

Edit: I'm no fan of .Nets built in authentication, Example goes in Global.asax:

    protected void Application_AcquireRequestState(object sender, EventArgs e)
    {
        try
        {
            string lcReqPath = Request.Path.ToLower();

            // Session is not stable in AcquireRequestState - Use Current.Session instead.
            System.Web.SessionState.HttpSessionState curSession = HttpContext.Current.Session;

            // If we do not have a OK Logon (remember Session["LogonOK"] = null; on logout, and set to true on logon.)
            //  and we are not already on loginpage, redirect.

            // note: on missing pages curSession is null, Test this without 'curSession == null || ' and catch exception.
            if (lcReqPath != "/loginpage.aspx" &&
                (curSession == null || curSession["LogonOK"] == null))
            {
                // Redirect nicely
                Context.Server.ClearError();
                Context.Response.AddHeader("Location", "/LoginPage.aspx");
                Context.Response.TrySkipIisCustomErrors = true;
                Context.Response.StatusCode = (int) System.Net.HttpStatusCode.Redirect;
                // End now end the current request so we dont leak.
                Context.Response.Output.Close();
                Context.Response.End();
                return;
            }
        }
        catch (Exception)
        {

            // todo: handle exceptions nicely!
        }
    }