ASP.NET MVC5 属性路由 - 只有一个匹配操作的模糊操作异常

Question

I have a weird bug that keeps popping up, usually while debugging, where I will get one route throwing this exception out of nowhere, and will continue for that route until I stop debugging. Weird thing is I only have one action that would ever match, and only one action with that name, only controller, etc.

My question is, has anyone come across such weird behavior? Any fixes? This has persisted after a repair install of Visual Studio 2019, reboots, etc. I think its an issue with the project but I can't find anything with a google search and I have no clue where to even begin looking. There's no way it's matching against the fallback route in the RouteConfig.cs AND the attribute route, right?

Update: Happened even following suggestions to clean up the similar routes in routeconfig.cs, happening on a seperate controller (another attribute routed controller). Details added below.

The current request is ambiguous between the following action methods:

System.Web.Mvc.ActionResult Getquestions(System.String, System.String, System.Web.Mvc.FormCollection) on type >Origin2.Controllers.Events2.Events2APIController

System.Web.Mvc.ActionResult Getquestions(System.String, System.String, System.Web.Mvc.FormCollection) on type >Origin2.Controllers.Events2.Events2APIController

Trimmed down controller:

using ...


namespace Origin2.Controllers.Events2
{

    [RoutePrefix("app/api/Events")]


    public class Events2APIController : Controller
    {

        [Route("{code}/questions/GET")]
        [HttpPost]
        public ActionResult Getquestions(string code, string mode, FormCollection collection)
        {
            //CODE LIVES HERE. 
        }

        protected override void OnException(ExceptionContext filterContext)
        {
            ExceptionNotifications.SendNotice(filterContext, null, "Events2 API Controller");
        }


    }

}

Trimmed down routeconfig.cs

using Origin2.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
namespace Origin2
{
    public class RouteConfig
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapMvcAttributeRoutes(); //Attribute Routing Enabled


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

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

            routes.MapRoute(
                name: "app2",
                url: "app/{action}",
                defaults: new { controller = "app", action = "Index" }
            );

            routes.MapRoute(
                name: "DefaultApp",
                url: "app/{controller}/{action}/{**id}",
                defaults: new { controller = "app", action = "Index", id = UrlParameter.Optional }
            );
            routes.MapRoute(
                name: "DefaultApp2",
                url: "app/{controller}/{action}",
                defaults: new { controller = "app", action = "Index" }
            );
            routes.MapRoute(
                name: "DebugShorthand",
                url: "debug",
                defaults: new { controller = "app", action = "Debug" }
            );
            routes.MapRoute(
                name: "RootAddress",
                url: "",
                defaults: new { controller = "app", action = "Index" }
            );
            routes.MapRoute(
                name: "DefaultOrigin1",
                url: "app/{*url}",
                defaults: new { controller = "app", action = "SendToOrigin1" }
            );
        }
    }
}

After fixing routeconfig.cs's ambiguous route.

The current request is ambiguous between the following action methods:

System.Web.Mvc.ActionResult EventLanding(System.String) on type Origin2.Controllers.Events2.Events2Controller

System.Web.Mvc.ActionResult EventLanding(System.String) on type Origin2.Controllers.Events2.Events2Controller

Trimmed down Events2Controller:

using Origin2.Models;
using Origin2.Models.Events2;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using static Origin2.Models.Events2.EventRoles;

namespace Origin2.Controllers.Events2
{
   [RoutePrefix("app/Events")]
   [Route("{action=index}")] 

  public class Events2Controller : Controller
    {

        [Route("{code}")]
        public ActionResult EventLanding(string code)
        {
            //This will be the public facing thank you handler for all signup activities. 
            if (code.ToUpper() == "AAABD") 
            {
                return View("EventLandingCustom_AAABD");
            }
            return View();
        }

        protected override void OnException(ExceptionContext filterContext)
        {
            ExceptionNotifications.SendNotice(filterContext, null, "Events2 Controller");

            // Redirect on error:
            //filterContext.Result = RedirectToAction("Error", "Index");
        }
   }
}

Answer 1

I think these two routes are identical

routes.MapRoute(
            name: "DefaultApp",
            url: "app/{controller}/{action}/{**id}",
            defaults: new { controller = "app", action = "Index", id = UrlParameter.Optional }
        );
        routes.MapRoute(
            name: "DefaultApp2",
            url: "app/{controller}/{action}",
            defaults: new { controller = "app", action = "Index" }

try commenting out one of these.