Why my custom 404 error handler does not work after deployed to web server

Question

I followed this post and created a global error handler. And I added to handle 404 error myself. however, it works fine when I test locally but once deployed to web server, my custom message is not displaying anymore. Instead, the default ugly one shows up.

In remote debug, I can trace the execution and it does get to my custom 404 error action, but somehow, the IIS took over at some point.

In my Global.asax.cs, I have:

protected void Application_Error()
{
    var exception = Server.GetLastError();
    var httpException = exception as HttpException;

    Response.Clear();
    Server.ClearError();

    var routeData = new RouteData();
    routeData.Values["controller"] = "Error";
    routeData.Values["action"] = "General";
    routeData.Values["exception"] = exception;

    Response.StatusCode = 500;

    if (httpException != null)
    {
        Response.StatusCode = httpException.GetHttpCode();

        switch (Response.StatusCode)
        {
            case 403:
                routeData.Values["action"] = "Http403";
                break;
            case 404:
                routeData.Values["action"] = "Http404";
                break;
        }
    }

    IController errorController = new ErrorController();
    var rc = new RequestContext(new HttpContextWrapper(Context), routeData);
    errorController.Execute(rc);
}

then in my ErrorHandler.cs, I have:

public ActionResult General(Exception exception)
{
    // log error

    return Content("General error", "text/html");
}

public ActionResult Http403(Exception exception)
{
    return Content("Forbidden", "text/plain");
}

public ActionResult Http404(Exception exception)
{
    return Content("Page not found.", "text/plain"); // this displays when tested locally, but not after deployed to web server.
}

}

Answer 1

You are right, remote IIS is taking over your 404 pages. What you need is to tell the IIS to skip custom errors setting Response.TrySkipIisCustomErrors = true;

So your code should look like this.

protected void Application_Error()
{
    //...
    Response.TrySkipIisCustomErrors = true;
    Response.StatusCode = 404;
    //...rest of your code
}

Also check this link for more information http://www.west-wind.com/weblog/posts/2009/Apr/29/IIS-7-Error-Pages-taking-over-500-Errors