c# - ASP.NET MVC 5 error handling

Question

We want to handle 403 errors, 404 errors, all errors due to a MySpecialDomainException and provide a default error page for all other errors (including errors in the IIS configuration!). All errors should return proper Razor views, it would be very nice to have an ErrorController in front of the views. E.g. something like this:

public class ErrorController : Controller
{
    public ViewResult NotFound () { return View(); }
    public ViewResult Forbidden () { return View(); }
    public ViewResult Default ()
    {
        var ex = ObtainExceptionFromSomewhere();
        if(ex is MySpecialDomainException)
            return View("MySpecialDomainException", new ErrorModel { Exception = ex });

        return View("GeneralError", new ErrorModel { Exception = ex });
    }
}

Currently you find many different ways to do that on the www, some most probably outdated. Among those:

• Controller.OnException()
• Error filter
• customErrors element in web.config
• Handling in Global.asax's Application_Error

Q1: What is the recommended way to fulfill our requirements with ASP.NET MVC 5?

Also we want to catch errors occurring in the IIS host. Q2: To prevent that IIS has to handle any 404s we thought about adding a default route matching all possible URLs - is this recommendable? Better to register instead for IIS' 404s as well?

Q3: Is it even possible to register an IIS error page which goes back to a controller, or is IIS capable of ASPX / static HTML only?

Answer 1

The best way is using Global.Asax, because you can manage all types of errors (Ajax calls/ all of unexpected Errors). with others you can't do it.

Like this:

protected void Application_Error()
{
    HttpContext httpContext = HttpContext.Current;
    if (httpContext != null)
    {
        RequestContext requestContext = ((MvcHandler)httpContext.CurrentHandler).RequestContext;
        /* When the request is ajax the system can automatically handle a mistake with a JSON response. 
           Then overwrites the default response */
        if (requestContext.HttpContext.Request.IsAjaxRequest())
        {
            httpContext.Response.Clear();
            string controllerName = requestContext.RouteData.GetRequiredString("controller");
            IControllerFactory factory = ControllerBuilder.Current.GetControllerFactory();
            IController controller = factory.CreateController(requestContext, controllerName);
            ControllerContext controllerContext = new ControllerContext(requestContext, (ControllerBase)controller);

            JsonResult jsonResult = new JsonResult
            {
                Data = new { success = false, serverError = "500" },
                JsonRequestBehavior = JsonRequestBehavior.AllowGet
            };
            jsonResult.ExecuteResult(controllerContext);
            httpContext.Response.End();
        }
        else
        {
            httpContext.Response.Redirect("~/Error");
        }
    }
}