This is a collection of common mistakes:
When trying to start a server, host, or client by executing one of these lines of code
NetworkingManager.Singleton.StartServer() NetworkingManager.Singleton.StartHost() NetworkingManager.Singleton.StartClient()
the following exception is thrown:
NullReferenceException: Object reference not set to an instance of an object
You most likely forgot to add the
NetworkingManager component to a game object in your scene.