404 Hubs Not Found And Debugging Problems

By: Nicklas Møller Jepsen


When working with SignalR I sometimes stumble upon some irritating problems that mostly seems related to Visual Studio and maybe also related to the SignalR framework being relatively new.

In this post I have assembled some of the errors I have been facing while developing with SignalR.

404 Hub(s) not found

This error seems to have a different solution whether you have deployed your app to IIS or you are debugging.


I have experienced a lot of difficulties while debugging/running my SignalR apps in Visual Studio 2013. Sometimes, when I reopen a solution that previously “just worked”, it all of the sudden don’t anymore, meaning that the ~/signalr/hubs gives a 404 on localhost or the client can not be found. A fix for this seems to be the following:

  1. Close Visual Studio
  2. Make sure IIS Express is shutdown also (look for the IIS Express tray icon)
  3. Start Visual Studio

If the above doesn't work, sometimes going out for a cup of coffee and returning does :)

Deployed on IIS

This is most likely related to the hub reference and how you are hosting the SignalR site on the server. I have written a post about the case, which you can find right here.


Remember that you can enable detailed errors when trying to troubleshoot SignalR related problems. Just add this to your OWIN Startup.cs:

var hubConfiguration = new HubConfiguration
	EnableDetailedErrors = true,
app.MapSignalR("/~/signalr", hubConfiguration);

Leave a comment if you have any other problems, and I'll be glad to try and help out!