Please see http://go.microsoft.com/fwlink/?LinkId=272764 for more information on using SignalR. Mapping the Hubs connection ---------------------------- SignalR Hubs will not work without a Hub route being configured. To register the default Hubs route, call RouteTable.Routes.MapHubs() in your application's Application_Start method, e.g.: using System; using System.Web; using System.Web.Routing; namespace MyWebApplication { public class Global : System.Web.HttpApplication { public void Application_Start() { // Register the default hubs route: ~/signalr RouteTable.Routes.MapHubs(); } } } Why does ~/signalr/hubs return 404 or Why do I get a JavaScript error: 'myhub is undefined'? -------------------------------------------------------------------------------------------- This issue is generally due to a missing or invalid script reference to the auto-generated Hub JavaScript proxy at '~/signalr/hubs'. Please make sure that the Hub route is registered before any other routes in your application. In ASP.NET MVC 4 you can do the following: If you're writing an ASP.NET MVC 3 application, make sure that you are using Url.Content for your script references: If you're writing a regular ASP.NET application use ResolveClientUrl for your script references or register them via the ScriptManager using a app root relative path (starting with a '~/'): If the above still doesn't work, you may have an issue with routing and extensionless URLs. To fix this, ensure you have the latest patches installed for IIS and ASP.NET.