A route named 'DefaultApi' is already in the route collection

Question

This question may seems duplicate but this is slightly different. In all other question in SO I had noticed that they have multiple routes registered. but in my case I have just one route.

I am creating asp.net webapi (framework 4.5) and have just one route in RegisterRoutes() method -

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

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

    }

Then why is it throwing error?

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

Answer 1

Fine, I resolved it based on the reply by user3038092. Instead of adding it in the route collection, I added it in HttpConfiguration

        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "rest/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

And it worked.