Yet another one of these questions, but I could not find an answer to why I am getting this error in any of the others.

I have my routes set up as:

 public class ContentRoutes
 {
 public static void Map(RouteCollection _routes)
 {
 _routes.MapHttpRoute(
 name: "GetThumbnail",
 routeTemplate: "api/content/thumbnail/{_id}",
 defaults: new { controller = "Content", id = "GetThumbnail" }
 );

 _routes.MapHttpRoute(
 name: "GetFile",
 routeTemplate: "api/content/file/{_id}",
 defaults: new { controller = "Content", id = "GetFile" }
 );
 }
 }

Which I am trying to map to my controller methods, which are declared as:

 [AcceptVerbs("GET")]
 public HttpResponseMessage GetThumbnail(int _id)

 [AcceptVerbs("GET")]
 public HttpResponseMessage GetFile(int _id)

When trying to access either of these, I am getting the error shown in the question title. I must be missing something obvious but I can not put my finger on it. Any ideas?