If you use a custom dependency resolver with SignalR, you can no longer use GlobalHost unless you modify it:
GlobalHost.DependencyResolver = new AutofacDependencyResolver(container);
IHubContext hubContext = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
// A custom HubConfiguration is now unnecessary, since MapSignalR will
// use the resolver from GlobalHost by default.
app.MapSignalR();
If you don’t want to modify GlobalHost, you will have to manually resolve your IConnectionManager:
IDependencyResolver resolver = new AutofacDependencyResolver(container);
IHubContext hubContext = resolver.Resolve<IConnectionManager>().GetHubContext<MyHub>();
app.MapSignalR(new HubConfiguration
{
Resolver = resolver
});