Handling 404 Not Found globally in MVC applications

The Kentico.Web.Mvc integration package includes a feature that allows you to return the same ‘404 Not Found’ page in the MVC application in the following scenarios:

• A suitable controller is not found
• A suitable controller action is not found
• A controller action returns System.Web.Mvc.HttpNotFoundResult (usually returned by calling the controller’s HttpNotFound method)

Prerequisite

The <modules> element in the <system.webServer> section of your MVC project’s main web.config file must have the runAllManagedModulesForAllRequests attribute set to true. The attribute is automatically added by installing the Kentico.Web.Mvc integration package.

<system.webServer>
...
    <modules runAllManagedModulesForAllRequests="true"></modules> 
...
</system.webSever> 

Enabling the global Not Found handler in MVC applications

1. If necessary, set up your Kentico instance and MVC application (see Starting with MVC development).

2.  Verify that the Not Found handler feature is enabled in the MVC project’s ApplicationConfig.cs file:

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    using Kentico.Web.Mvc;
   
    ...
   
    public static void RegisterFeatures(ApplicationBuilder builder)
    {
        ...
        builder.UseNotFoundHandler();
        ...
    }
   
   
    

3. Create a NotFound.cshtml view under the Views\Shared path in your MVC project.

4. Implement the content of the view to design your site’s Not found page.

Now whenever a request for a page that does not match any controller or controller action is made, the system returns the NotFound.cshtml page. The system also returns the page whenever a controller action returns the *System.Web.Mvc.**HttpNotFoundResult* class (for example, when calling the System.Web.Mvc.Controller.HttpNotFound method).

Handling requests not matched by any route

You can also return the  NotFound.cshtml view in other cases in which the MVC application responds with a ‘Not Found’ status. To cover a scenario when a request that does not match any configured route is made, you need to implement a catch-all route in the RouteConfig.cs file.

1. Create a new catch-all route in the MVC application’s RouteConfig.cs file. Make sure the route is the last route that you register in the file:

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    public static void RegisterRoutes(RouteCollection routes)
    {
        ...
        routes.MapRoute(
            name: "NotFound",
            url: "{*url}",
            defaults: new { controller = "HttpErrors", action = "NotFound" }
        ); 
    }
   
   
    

2. Create a controller and action for the catch-all route.

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    public class HttpErrorsController : Controller
    {
        public ActionResult NotFound()
        {
            Response.StatusCode = 404;
            Response.TrySkipIisCustomErrors = true;
   
            return View();
        }
    }
   
   
    

The system returns the NotFound.cshtml page whenever a request for an undefined route is made on the MVC site.