Signalr negotiate url fails

OK, found it out myself. Spelling error. The name of the hub mentioned was incorrect.

changed:
var proxy = this.connection.createHubProxy('chattAppHub');

to:
var proxy = this.connection.createHubProxy('ChatAppHub');

In the backend:
[HubName("ChatAppHub")]
public class ChatAppHub : Hub ...

inside startup.cs
var hubConfiguration = new HubConfiguration(); hubConfiguration.EnableDetailedErrors = true; appBuilder.MapSignalR(hubConfiguration); appBuilder.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);