Too many applications are caused by the busy system. You can log in again after logging out.
The function of health code is not to prove that you are healthy, otherwise you are not allowed to declare your physical condition and then report it. It is actually similar to the QR code of an electronic identity.
Exception in querying travel itinerary code display service. Generally speaking, the system is still under maintenance. Another possibility is that your network is not good. Try reconnecting to the network.