A route named “x” is already in the route collection. Route names must be unique. Exception with ASP.NET MVC 3

吃可爱长大的小学妹 提交于 2019-11-27 11:44:26

To fix this problem I had to go into the bin folder on my project, delete all DLL files and then rebuild and this fixed the problem.

This error can occur due to multiple causes, I had the same error and solved it by modifying the Global.asax class.

The Application_Start method at Global.asax.cs was like:

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    BundleConfig.RegisterBundles(BundleTable.Bundles);
}

The following line occurs twice in this method:

RouteConfig.RegisterRoutes(RouteTable.Routes);

This ensured that the route was twice added to the route list and at the same time causing the error.

I changed the Application_Start method as follows and the error disappeared:

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    AreaRegistration.RegisterAllAreas();
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    BundleConfig.RegisterBundles(BundleTable.Bundles);
}

This may not be the answer for your problem, but can perhaps help others in the future. I didn't see this answer between the others, so I decided to add this.

I found out that Global.asax was referring to an old version of the site's DLL file before I renamed it. The DLL was not being cleaned up when I did Build > Clean up because the VS project/solution didn't refer to it any more. It seems that sometimes only the newer version of the DLL was being used, allowing the site to work correctly, but eventually both of them would be loaded causing the route conflicts.

The routes get loaded from all assemblies within AppDomain.CurrentDomain, so if your old assemblies are still part of that, you might be still getting old/duplicate routes.

In my case, I faced with this issue, when I added reference to another project from solution, which also was MVC and use the same names in area (I didn't want to added this project, I don't know how it happened). When I removed this DLL, project started to work.

Deleting the DLLs alone didn't work for me (in VS2013), but deleting the entire 'bin' and 'obj' folders and then building the solution worked perfectly! Makes me wish I hadn't spent so long trying to fix it...

None of the suggestions worked for me. Went ahead and restarted the web server (IIS in this case) and that cleared the error after I had fixed the code. DLL must have been cached in IIS.

I am getting same error. But finally I have got solution. Scenario: I am adding different(mvc4 application) dll in my web api mvc4 application. When try to run. I am getting same error. Root Cause- When my web api application run .Application register all area from self and start loading to current application domain dll references. When application load dll(MVC4 application) that time getting error because current maproute already add key for "HelpPage_Default".

Solution. 1.Change key for RegisterArea in maproute either current application or existing application(Refer dll). 2.Move code dll(mvc4 application) code to different liberary and refer to new dll.

I was manually calling AttributeRoutingHttpConfig.Start() in my Global.asax. Did not notice this auto-generated line at the top of the file which automatically calls it.

[assembly: WebActivator.PreApplicationStartMethod(typeof(Mev.Events.Web.AttributeRoutingHttpConfig), "Start")]

I had an application that was a Forms app migrated to MVC with a third party component used for authentication which redirected to another site. The component would start a session twice if the user wasn't already logged in (once for initial connection to site and once for return). So I solved this with the following code:

if (routes.Count < 3)
            {
                routes.IgnoreRoute("login.aspx");
                routes.IgnoreRoute("default.aspx");
                routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

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

Deleting the dlls in the bin folder did work 100%, I still had dlls my project needed to rebuild. Rather make a copy of the bin folder. then delete the original.rebuild the project. if it fails, place the missing dlls into the bin folder.

I was running an old MVC2 website and I got this issue because the IIS 'Managed Pipeline Mode' was set on 'Integrated' by default (press F4 on the project). Changing it to 'Classic' fixed the issue

Mahadev Sharma

try this code, only change name

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