Question

I have a MVC app that is loading a external DLL and when in production I get no error at all. Firefox just says the connection was reset. So I put some try/catch in the code but they still do not work, I still get the connection reset message.

I know the error is a BadImageFormatException but why don’t I see anything in the browser?

 public class HomeController : Controller
    {

        [DllImport("CDCrypt.dll")]
        [return: MarshalAs(UnmanagedType.LPStr)]
        public static extern String Encrypt([MarshalAs(UnmanagedType.LPStr)] String aName);



        [DllImport("CDCrypt.dll")]
        [return: MarshalAs(UnmanagedType.LPStr)]
        public static extern String Decrypt([MarshalAs(UnmanagedType.LPStr)] String aName);


        //
        // GET: /Home/

        public ActionResult Index()
        {

            try
            {
                ViewBag.EncryptString = Encrypt("test");
            }
            catch (Exception e)
            {
                ViewBag.EncryptString = "Stack Trace\r\n:" + "\r\nException: " + e.Message;
                return new HttpStatusCodeResult(500);
            }
            return View();
        }

        public ActionResult Up()
        {
            ViewBag.Up = "You can see me";
            return View();
        }



    }

Answer 1

There seem to be some exceptions which are marked as unrecoverable and so cannot be caught. This question (well this answer really) has a list of them, but I don’t know how exhaustive this is.

This article has some more information about uncatchable exceptions, and how they can be caught if you throw them but not if the runtime throws them.

This question says that doing a catch rather than a catch(Exception ex) will allow COM exceptions to be caught as well. Don’t know if this will help (I doubt it) but is interesting, and might.