Unable to determine websocket handshake problem

[johaven]

Versions

• python
  Flask-SocketIO 5.1.1
  python-socketio 5.4.0
  python-engineio 4.2.1
• js
  [email protected]

Problem

In the previous releases we could see "invalid transport" message or others messages helping.
In this case, python-socketio return a 400 error with no messages, i can't determine the problem.

socketio = SocketIO(app, client_manager=client_manager, json=json, cookie=None, logger=True, engineio_logger=True)

127.0.0.1:5000 [pid: 3704|app: 0|req: 1/1] 127.0.0.1 () {58 vars in 2217 bytes} [Fri Sep 10 16:46:16 2021] GET /socket.io/?EIO=4&transport=websocket => generated 13 bytes in 2 msecs (HTTP/1.1 400) 4 headers in 170 bytes (3 switches on core 249)
7XNrQ8VAes8b77zGAAAA: Sending packet PING data None
7XNrQ8VAes8b77zGAAAA: Client is gone, closing socket
7XNrQ8VAes8b77zGAAAA: Client is gone, closing socket
lGxlYJs9T2QUzaEeAAAB: Sending packet OPEN data {'sid': 'lGxlYJs9T2QUzaEeAAAB', 'upgrades': [], 'pingTimeout': 20000, 'pingInterval': 25000}
lGxlYJs9T2QUzaEeAAAB: Received request to upgrade to websocket
127.0.0.1:5000 [pid: 3704|app: 0|req: 2/2] 127.0.0.1 () {58 vars in 2217 bytes} [Fri Sep 10 16:47:16 2021] GET /socket.io/?EIO=4&transport=websocket => generated 13 bytes in 0 msecs (HTTP/1.1 400) 4 headers in 170 bytes (3 switches on core 249)
lGxlYJs9T2QUzaEeAAAB: Sending packet PING data None
lGxlYJs9T2QUzaEeAAAB: Client is gone, closing socket
lGxlYJs9T2QUzaEeAAAB: Client is gone, closing socket
Yr9eAcmim60BGZetAAAC: Sending packet OPEN data {'sid': 'Yr9eAcmim60BGZetAAAC', 'upgrades': [], 'pingTimeout': 20000, 'pingInterval': 25000}
Yr9eAcmim60BGZetAAAC: Received request to upgrade to websocket
127.0.0.1:5000 [pid: 3704|app: 0|req: 3/3] 127.0.0.1 () {58 vars in 2217 bytes} [Fri Sep 10 16:48:16 2021] GET /socket.io/?EIO=4&transport=websocket => generated 13 bytes in 0 msecs (HTTP/1.1 400) 4 headers in 170 bytes (3 switches on core 249)
Yr9eAcmim60BGZetAAAC: Sending packet PING data None

[miguelgrinberg]

The error is in your logs: "Client is gone, closing socket". The server is sending a PING packet, and the client is not responding with a PONG.

[johaven]

Related to: #1681

SocketIO Server used the 'gevent' driver instead of 'gevent_uwsgi'