How can I properly handle 404 in ASP.NET MVC?

Question

I am using RC2

Using URL Routing:

routes.MapRoute(
    \"Error\",
     \"{*url}\",
     new { controller = \"Errors\", action = \"N         


        

Answer 1

Dealing with errors in ASP.NET MVC is just a pain in the butt. I tried a whole lot of suggestions on this page and on other questions and sites and nothing works good. One suggestion was to handle errors on web.config inside system.webserver but that just returns blank pages.

My goal when coming up with this solution was to;

• NOT REDIRECT
• Return PROPER STATUS CODES not 200/Ok like the default error handling

Here is my solution.

1.Add the following to system.web section

The above handles any urls not handled by routes.config and unhandled exceptions especially those encountered on the views. Notice I used aspx not html. This is so I can add a response code on the code behind.

2. Create a folder called Error (or whatever you prefer) at the root of your project and add the two webforms. Below is my 404 page;

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="404.aspx.cs" Inherits="Myapp.Error._404" %>




    
    
    
    " rel="stylesheet" />


    

      
    
    

        
404 - Page Not found
        
The page you are looking for cannot be found.
        

        

    

And on the code behind I set the response code

protected void Page_Load(object sender, EventArgs e)
{
    Response.StatusCode = 404;
}

Do the same for the 500 page

3.To handle errors within the controllers. There's many ways to do it. This is what worked for me. All my controllers inherit from a base controller. In the base controller, I have the following methods

protected ActionResult ShowNotFound()
{
    return ShowNotFound("Page not found....");
}

protected ActionResult ShowNotFound(string message)
{
    return ShowCustomError(HttpStatusCode.NotFound, message);
}

protected ActionResult ShowServerError()
{
    return ShowServerError("Application error....");
}

protected ActionResult ShowServerError(string message)
{
    return ShowCustomError(HttpStatusCode.InternalServerError, message);
}

protected ActionResult ShowNotAuthorized()
{
    return ShowNotAuthorized("You are not allowed ....");

}

protected ActionResult ShowNotAuthorized(string message)
{
    return ShowCustomError(HttpStatusCode.Forbidden, message);
}

protected ActionResult ShowCustomError(HttpStatusCode statusCode, string message)
{
    Response.StatusCode = (int)statusCode;
    string title = "";
    switch (statusCode)
    {
        case HttpStatusCode.NotFound:
            title = "404 - Not found";
            break;
        case HttpStatusCode.Forbidden:
            title = "403 - Access Denied";
            break;
        default:
            title = "500 - Application Error";
            break;
    }
    ViewBag.Title = title;
    ViewBag.Message = message;
    return View("CustomError");
}

4.Add the CustomError.cshtml to your Shared views folder. Below is mine;

@ViewBag.Title


@ViewBag.Message

Now in your application controller you can do something like this;

public class WidgetsController : ControllerBase
{
  [HttpGet]
  public ActionResult Edit(int id)
  {
    Try
    {
       var widget = db.getWidgetById(id);
       if(widget == null)
          return ShowNotFound();
          //or return ShowNotFound("Invalid widget!");
       return View(widget);
    }
    catch(Exception ex)
    {
       //log error
       logger.Error(ex)
       return ShowServerError();
    }
  }
}

Now for the caveat. It won't handle static file errors. So if you have a route such as example.com/widgets and the user changes it to example.com/widgets.html, they will get the IIS default error page so you have to handle IIS level errors some other way.