SignalR Cross-domain Javascript Client Hub Start Method Fails Only When Client Methods Are Subscribed

SignalR cross-domain javascript client hub start method fails only when client methods are subscribed. If client methods are not subscribed, hub start is successfully called and th

Solution 1:

Response status 500 (Internal Server Error) is about a null reference in the OnConnected method of the Hub. Was able to figure that out using the Fiddler.

Solution 2:

On the front end make sure you are NOT setting cors support

jQuery.support.cors = true //Do not put this

On the server, in your startup class, make sure cors is allowed by adding:

  app.Map("/signalr", map =>
        {
            // Setup the CORS middleware to run before SignalR.
            // By default this will allow all origins. You can 
            // configure the set of origins and/or http verbs by
            // providing a cors options with a different policy.
            map.UseCors(CorsOptions.AllowAll);
            var hubConfiguration = new HubConfiguration 
            {
                // You can enable JSONP by uncommenting line below.
                // JSONP requests are insecure but some older browsers (and some
                // versions of IE) require JSONP to work cross domain
                // EnableJSONP = true
            };
            // Run the SignalR pipeline. We're not using MapSignalR
            // since this branch already runs under the "/signalr"
            // path.
            map.RunSignalR(hubConfiguration);
        });

Info on Cors/JSONP support can be found at: asp net