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

Question

I'm doing an ASP.NET MVC 3 web service and I keep getting this exception intermittently.

Stack trace:

Server Error in '/' Application.

A route named 'ListTables' is already in the route collection. Route names must be unique.
Parameter name: name

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentException: A route named 'ListTables' is already in the route collection. Route names must be unique.
Parameter name: name

Source Error: 


Line 24:            //     }
Line 25:            // );
Line 26:             context.MapRoute(
Line 27:                 "ListTables",
Line 28:                 // example: 

Source File: C:\inetpub\wwwroot\SchemaBrowserService\Website\Areas\Api\ApiAreaRegistration.cs    Line: 26 

Stack Trace: 


[ArgumentException: A route named 'ListTables' is already in the route collection. Route names must be unique.
Parameter name: name]
   System.Web.Routing.RouteCollection.Add(String name, RouteBase item) +2329682
   System.Web.Mvc.RouteCollectionExtensions.MapRoute(RouteCollection routes, String name, String url, Object defaults, Object constraints, String[] namespaces) +236
   System.Web.Mvc.AreaRegistrationContext.MapRoute(String name, String url, Object defaults, Object constraints, String[] namespaces) +59
   System.Web.Mvc.AreaRegistrationContext.MapRoute(String name, String url, Object defaults) +17
   SchemaBrowserService.Areas.Api.ApiAreaRegistration.RegisterArea(AreaRegistrationContext context) in C:\inetpub\wwwroot\SchemaBrowserService\Website\Areas\Api\ApiAreaRegistration.cs:26
   System.Web.Mvc.AreaRegistration.CreateContextAndRegister(RouteCollection routes, Object state) +105
   System.Web.Mvc.AreaRegistration.RegisterAllAreas(RouteCollection routes, IBuildManager buildManager, Object state) +199
   System.Web.Mvc.AreaRegistration.RegisterAllAreas(Object state) +45
   System.Web.Mvc.AreaRegistration.RegisterAllAreas() +6
   Website.MvcApplication.Application_Start() in C:\Users\djackson\Downloads\RestApiMvc3\Website\Website\Global.asax.cs:35

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

It's probably related to the fact that Route Debugger shows that I have some old routes that I've modified or deleted and won't go away (even after rebooting my machine). The stack trace also refers to a source file that has long since been deleted and my app has been moved to a new location, cleaned and rebuilt since then. What am I missing?

Here is all of my route registration code:

// in Global.asax.cs:
public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    routes.MapRoute(
        "Default2", // Route name
        "Api/{controller}/{action}/{id}", // URL with parameters
        new { controller = "DataSource", action = "Index", area = "Api", id = UrlParameter.Optional } // Parameter defaults
        );

        routes.MapRoute(
            "Default", // Route name
            "{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
        );

    }

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    RegisterRoutes(RouteTable.Routes);
}

// in ApiAreaRegistration.cs:
public class ApiAreaRegistration : AreaRegistration
{
    public override string AreaName { get { return "Api"; } }

    public override void RegisterArea(AreaRegistrationContext context)
    {
        // DataSources

        // Tables
        context.MapRoute(
            "ListTables",
            // example: 
            // /api/DataSources/DataSource/1/schemata/schema/dbo/tables
               "Api/DataSources/DataSource/{dataSourceId}/schemata/{schemaName}/tables",
            new
            {
                controller = "Tables",
                action = "TableList",
                schemaName = "dbo",
                dataSourceId = "DefaultId"
            }
        );


        // Schemata
        context.MapRoute(
          "Schema",
            // example: 
            // /api/DataSources/DataSource/1/schemata/schema/dbo
              "Api/DataSources/DataSource/{dataSourceId}/schemata/{schemaName}",
          new
          {
              controller = "Schema",
              action = "Schema",
              dataSourceId = "DefaultId",
              schemaName = UrlParameter.Optional
          }
       );

       // // DataSources
        context.MapRoute(
            "SingleDataSource",
            "Api/DataSources/DataSource/{dataSourceId}",
            new
            {
                controller = "DataSource",
                action = "DataSource",
                dataSourceId = UrlParameter.Optional
            }
        );
        context.MapRoute(
            "ListDataSources",
            "Api/DataSources",
            new
            {
                controller = "DataSource",
                action = "DataSourceList",
                dataSourceId = "DefaultId"
            }
        );
        context.MapRoute(
             "Api_default",
             "Api/{controller}/{action}/{id}",
             new { action = "Index", id = UrlParameter.Optional }
        );

    }
}

Answer 1

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.