CustomErrors vs HttpErrors - A significant design flaw?

Question

As we might know, from e.g. What is the difference between customErrors and httpErrors?, CustomErrors is a older way to define error pages in a web application but this appr

Answer 1

Just like you, I think ASP.NET shouldn't set TrySkipIisCustomErrors or may add an option so we can avoid it.

As a workaround, I built an ASPX page that is able to transfer the query to an ASP.NET MVC Controller.

ErrorHandler.aspx.cs

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ErrorHandler.aspx.cs" Inherits="Guillaume.ErrorHandler" %>

Code behind

protected void Page_Load(object sender, EventArgs e)
{
  //Get status code
  var queryStatusCode = Request.QueryString.Get("code");
  int statusCode;
  if (!int.TryParse(queryStatusCode, out statusCode))
  {
    var lastError = Server.GetLastError();
    HttpException ex = lastError as HttpException;
    statusCode = ex == null ? 500 : ex.GetHttpCode();
  }
  Response.StatusCode = statusCode;

  // Execute a route
  RouteData routeData = new RouteData();
  string controllerName = Request.QueryString.Get("controller") ?? "Errors";
  routeData.Values.Add("controller", controllerName);
  routeData.Values.Add("action", Request.QueryString.Get("action") ?? "Index");

  var requestContext = new RequestContext(new HttpContextWrapper(Context), routeData);
  IController controller = ControllerBuilder.Current.GetControllerFactory().CreateController(requestContext, controllerName);
  controller.Execute(requestContext);
}

Usage in web.config

The behavior is correct on regular browser request : the error page is shown when there is an error and the error code is returned. It's also correct on an AJAX/Web API request : the error page is NOT returned. We get a parsable error in JSON or XML.

You may add a httpErrors section if you want non-ASP.NET errors to be redirected to your custom errors.