Multiple actions were found that match the request [duplicate]

Answer 1

The problem is in the order that the routes are loaded. If they are like this:

// A route that enables RPC requests
routes.MapHttpRoute(
    name: "RpcApi",
    routeTemplate: "rpc/{controller}/{action}",
    defaults: new { action = "Get" }
);

// Default route
routes.MapHttpRoute(
    name: "Default",
    routeTemplate: "{controller}/{id}",
   defaults: new { id =  RouteParameter.Optional }
);

It will work fine. First the request will be mapped against the RPC, then against the controller (thaty may have or not an Id).