RuntimeError: Unexpected ASGI message 'websocket.send', after sending 'websocket.close'

Question

• I am trying to build a chat server with two websocket endpoints. One for the room owners to create_room and second for others who wants to join the room.
• I have 'Room' and 'RoomManager' classes. Room has list of members, and other room info. where as 'RoomManager' helps in creating rooms and accepting people into the room.
• when a user tries to enter the room with room_id i am sending a request to the room_owner whether to add the member to the room. When user accepts I am adding the member to the list of members in the room.
• when a new user tries to enter a room and the owner accept it (by sending 'yes') I wanted to broadcast "xxxx has entered the room". When I try to broadcast it shows this error "RuntimeError: Unexpected ASGI message 'websocket.send', after sending 'websocket.close' ". This is the link to repo. I heard of sending ping pong framesbut did not find docs to implement it.

Files explanation in repo:

• app.py : contains http and websocket endpoints

• room_manager.py : has Room and RoomManager classes.

• connection_manger.py: default connection manager provided by fastapi docs. Used to store temporary connections before user is part of any room.

This is the link to the cmd log.

Answer 1

The error "RuntimeError: Unexpected ASGI message 'websocket.send', after sending 'websocket.close'" literally means that you are trying to send a message on a connection that was closed. From what I understand from your question you are keeping a list of users that are part of a room when a user enters the room and you are broadcasting this welcome message to all the other users of the room. But what if a user has disconnected or the underlying connection of a particular user s closed? In this case you'll get the above mentioned error.

What can solve this problem is you should always check for connection closed exception while reading/ writing messages on a connection and should mark the user disconnected if such exception occurs.