404–This is not the web page you are looking for

On a given website, not all users will type the right link, and your ASP.NET MVC pages will have the exact controller action to render a given view.  In such cases, you need a nice 404 page.  You can go as fancy as github’s 404.  Check this out.

You can achieve this and similar other errors tapping into the Application_Error handler in your Global.asax file:

 1  protected void Application_Error(object sender, EventArgs e)
 2         {
 3             var app = (MvcApplication)sender;
 4             var context = app.Context;
 5             var ex = app.Server.GetLastError();
 6             context.Response.Clear();
 7             context.ClearError();
 8             var httpException = ex as HttpException;
 9 
10             var routeData = new RouteData();
11             routeData.Values["controller"] = "Error";
12             routeData.Values["exception"] = ex;
13             routeData.Values["action"] = "http500";
14             if (httpException != null)
15             {
16                 switch (httpException.GetHttpCode())
17                 {
18                     case 404:
19                         routeData.Values["action"] = "http404";
20                         break;
21                    // implement other http statuses here as well.
22                 }
23             }
24             IController controller = new ErrorController();
25             controller.Execute(new RequestContext(new HttpContextWrapper(context), 
26                 routeData));
27         }

Then add an ErrorController.cs file and implement the below:

 1 namespace Http404NotFound.Controllers
 2 {
 3     public class ErrorController : Controller
 4     {
 5         public ActionResult Http404()
 6         {
 7             return View();
 8         }
 9 
10         // implementation of other status can go here...
11     }
12 }

Using the new Razor syntax and file format, The Http404.cshtml can look like this:

1 @{
2     ViewBag.Title = "Http404";
3 }
4 
5 <h2>Http404</h2>
6 <img src="../../Content/images/github_404.PNG" />
7 
8 

You can find more MVC Cook book recipes in ASP.NET MVC 2 Cookbook.

Happy Coding!