C# – CategoryRouteHandler() reference

Here is another scenario where you might confront this error. If you rename your project so that the file name of the assembly changes, it's possible for you to have two versions of your ASP.NET assembly, which will reproduce this error.

The solution is to go to your bin folder and delete the old dlls. (I tried "Rebuild Project", but that didn't delete 'em, so do make sure to check bin to ensure they're gone)

Maybe you should try to have your enums as integers instead?

This is how I did it

public enum ECacheType
{
    cache=1, none=2
}

public enum EFileType 
{
    t1=1, t2=2
}

public class TestController
{
    [Route("{type}/{library}/{version}/{file?}/{renew?}")]
    public ActionResult Index2(EFileType type,
                              string library,
                              string version,
                              string file = null,
                              ECacheType renew = ECacheType.cache)
    {
        return View("Index");
    }
}

And my routing file

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

    // To enable route attribute in controllers
    routes.MapMvcAttributeRoutes();

    routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional });
}

I can then make calls like

http://localhost:52392/2/lib1/ver1/file1/1
http://localhost:52392/2/lib1/ver1/file1
http://localhost:52392/2/lib1/ver1

or

http://localhost:52392/2/lib1/ver1/file1/1/
http://localhost:52392/2/lib1/ver1/file1/
http://localhost:52392/2/lib1/ver1/

and it works fine...