I have tried the following 2 things to have a page return a 404 error:
public ActionResult Index()
{
return new HttpStatusCodeResult(404);
}
public ActionResult NotFound()
{
return HttpNotFound();
}
but both of them just render a blank page. How can I manually return a 404 error from within ASP.NET MVC 3?
If you inspect the response using fiddler, I believe you'll find that the blank page is in fact returning a 404 status code. The problem is no view is being rendered and thus the blank page.
You could get an actual view to be displayed instead by adding a customErrors element to your web.config that will redirect the user to a specific url when a certain status code occurs which you can then handle as you would with any url. Here's a walk-through below:
First throw the HttpException where applicable. When instantiating the exception, be sure to use one of the overloads which takes a http status code as a parameter like below.
throw new HttpException(404, "NotFound");
Then add an custom error handler in your web.config file so that you could determine what view should be rendered when the above exception occurs. Here's an example below:
<configuration>
<system.web>
<customErrors mode="On">
<error statusCode="404" redirect="~/404"/>
</customErrors>
</system.web>
</configuration>
Now add a route entry in your Global.asax that'll handle the url "404" which will pass the request to a controller's action that'll display the View for your 404 page.
Global.asax
routes.MapRoute(
"404",
"404",
new { controller = "Commons", action = "HttpStatus404" }
);
CommonsController
public ActionResult HttpStatus404()
{
return View();
}
All that's left is to add a view for the above action.
One caveat with the above method: according to the book "Pro ASP.NET 4 in C# 2010" (Apress) the use of customErrors is outdated if you're using IIS 7. Instead you should use the httpErrors section. Here's a quote from the book:
But although this setting still works with Visual Studio’s built-in test web server, it’s effectively been replaced by the
<httpErrors>section in IIS 7.x.
Response.StatusCode = 404; into the controller function to not return a 200 status along with the 404 page.I'm successfully using this:
return new HttpNotFoundResult();
throw new HttpException(404, "NotFound"); along with a custom error handler works fine for me.
You should use
// returns 404 Not Found as EmptyResult() which is suitable for ajax calls
return new HttpNotFoundResult();
when you are making AJAX calls to your controllers and don't find any content.
When you are making classic calls to controller actions and returning Views you should use:
// throwing new exception returns 404 and redirects to the view defined in web.config <customErrors> section
throw new HttpException(404, ExceptionMessages.Error_404_ContentNotFound);
You can personalize 404 result with
return new HttpStatusCodeResult(404, "My message");
