Socket connection breaking frequently with flask-socketio

Question

I am using flask-socketio to make a socket connection from my python web server to the javascript client. I am able to establish the connection but it breaks in a while(5 seconds or so) with the error

socket.io.min.js:2 WebSocket connection to 'ws://localhost:5000/socket.io/?EIO=3&transport=websocket&sid=8ed663e14c6f47328b64f2d29a30d1cd' failed: Received a broken close frame containing invalid UTF-8.

Server side code to send the message(calling this periodically, say every 5 seconds)

def send_message(result):
    # it will forward the message to all clients.
    print("sending message")
    socketio.send("Send working",  json=False)

Client side code to receive the message

socket.on('message', function (data) {
    console.log('message form backend ' + data);
});

Somehow it breaks -> then nothing happens for a while -> then connect again automatically -> then breaks again.

Can someone please help? Thanks a lot!

Answer 1

I fixed it.

socketio = SocketIO(app,ping_timeout=5)

ping_timeout – The time in seconds that the client waits for the server to respond before disconnecting. So it will be disconnected after 5 seconds if you do nothing.

The solution is that: Make your client side send message to server before timeout.

Cause my server usually sends data, so I make my client side like:

socket.on('message', function (data) {
    console.log('message form backend ' + data);
    socket.send('data receive!');
});