Before asking a separate question I've done lots of googling about it and added a comment in the already existing stackoverflow question. I have a SignalR Hub (tried both v. 1.1.3 and 2.0.0-rc) in my server with the below code: [HubName("TestHub")] public class TestHub : Hub { [Authorize] public void TestMethod(string test) { //some stuff here Clients.Caller.NotifyOnTestCompleted(); } } The problem persists if I remove the Authorize attribute. And in my iOS client I try to call it with the below code: SRHubConnection *hubConnection = [SRHubConnection connectionWithURL:_baseURL]; SRHubProxy *hubProxy = [hubConnection createHubProxy:@"TestHub"]; [hubProxy on:@"NotifyOnTestCompleted" perform:self selector:@selector(stopConnection)]; hubConnection.started = ^{ [hubProxy invoke:@"TestMethod" withArgs:@[@"test"]]; }; //received, error handling [hubConnection start]; When the app starts the user is not logged in and there is no open SignalR connection. The users logs in by calling a Login service in the server which makes use of WebSecurity.Login method. If the login service returns success I then make the above call to SignalR Hub and I get the server error 500 with description "The ConnectionId is in the incorrect format.". The full server stacktrace is the following: Exception information: Exception type: InvalidOperationException Exception message: The ConnectionId is in the incorrect format. at Microsoft.AspNet.SignalR.PersistentConnection.GetConnectionId(HostContext context, String connectionToken) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(IDictionary`2 environment) at Microsoft.Owin.Mapping.MapMiddleware.<Invoke>d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Request information: Request URL: http://myserverip/signalr/signalr/connect?transport=webSockets&connectionToken=axJs EQMZxpmUopL36owSUkdhNs85E0fyB2XvV5R5znZfXYI/CiPbTRQ3kASc3 mq60cLkZU7coYo1P fbC0U1LR2rI6WIvCNIMOmv/mHut/Unt9mX3XFkQb053DmWgCan5zHA==&connectionData=[{"Name":"testhub"}] Request path: /signalr/signalr/connect User host address: User: Is authenticated: False Authentication Type: Thread account name: IIS APPPOOL\DefaultAppPool Thread information: Thread ID: 14 Thread account name: IIS APPPOOL\DefaultAppPool Is impersonating: True Stack trace: at Microsoft.AspNet.SignalR.PersistentConnection.GetConnectionId(HostContext context, String connectionToken) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(IDictionary`2 environment) at Microsoft.Owin.Mapping.MapMiddleware.<Invoke>d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) I understand this is some kind of authentication and user identity mismatching but up to now I have found no way of solving it. All other questions suggest stoping the opened connection when the user identity changes but as I mentioned above I have no open connection before the user logs in successfully. Any help would be much appreciated. Thank you.