All ASP.NET Web API controllers return 404

Question

I\'m trying to get an API Controller to work inside an ASP.NET MVC 4 web app. However, every request results in a 404 and I\'m stumped. :/

I have th

Answer 1

I'm going to add my solution here because I personally hate the ones which edit the web.config without explaining what is going on.

For me it was how the default Handler Mappings are set in IIS. To check this...

1. Open IIS Manager
2. Click on the root node of your server (usually the name of the server)
3. Open "Handler Mappings"
4. Under Actions in the right pane, click "View ordered list"

This is the order of handlers that process a request. If yours are like mine, the "ExtensionlessUrlHandler-*" handlers are all below the StaticFile handler. Well that isn't going to work because the StaticFile handler has a wildcard of * and will return a 404 before even getting to an extensionless controller.

So rearranging this and moving the "ExtensionlessUrlHandler-*" above the wildcard handlers of TRACE, OPTIONS and StaticFile will then have the Extensionless handler activated first and should allow your controllers, in any website running in the system, to respond correctly.

Note: This is basically what happens when you remove and add the modules in the web.config but a single place to solve it for everything. And it doesn't require extra code!