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

I went through most of the solutions posted on this thread. While this question might be old, it is still very applicable to new projects even now, so I spent quite a lot of time reading up on the answers presented here as well as else where.

As @Marco pointed out the different cases under which a 404 can happen, I checked the solution I compiled together against that list. In addition to his list of requirements, I also added one more.

• The solution should be able to handle MVC as well as AJAX/WebAPI calls in the most appropriate manner. (i.e. if 404 happens in MVC, it should show the Not Found page and if 404 happens in WebAPI, it should not hijack the XML/JSON response so that the consuming Javascript can parse it easily).

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This solution is 2 fold:

First part of it comes from @Guillaume at https://stackoverflow.com/a/27354140/2310818. Their solution takes care of any 404 that were caused due to invalid route, invalid controller and invalid action.

The idea is to create a WebForm and then make it call the NotFound action of your MVC Errors Controller. It does all of this without any redirect so you will not see a single 302 in Fiddler. The original URL is also preserved, which makes this solution fantastic!

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Second part of it comes from @Germán at https://stackoverflow.com/a/5536676/2310818. Their solution takes care of any 404 returned by your actions in the form of HttpNotFoundResult() or throw new HttpException()!

The idea is to have a filter look at the response as well as the exception thrown by your MVC controllers and to call the appropriate action in your Errors Controller. Again this solution works without any redirect and the original url is preserved!

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As you can see, both of these solutions together offer a very robust error handling mechanism and they achieve all the requirements listed by @Marco as well as my requirements. If you would like to see a working sample or a demo of this solution, please leave in the comments and I would be happy to put it together.