Flask-SocketIO Not Emitting Events After Upgrade to Flask 2.0
I'm learning this framework and I'm deploying to production and I've been banging my head against this for hours....... I'm experiencing an issue with Flask-SocketIO after upgrading to Flask 2.0. After the upgrade, the socket events that were previously working fine stopped emitting, and I'm receiving no errors in the console. I'm using Flask-SocketIO version 5.0.0 and Python 3.8. My current setup involves a simple Flask application where I handle socket events for a chat feature. Here’s a minimal example of my implementation: ```python from flask import Flask, render_template from flask_socketio import SocketIO, emit app = Flask(__name__) app.config['SECRET_KEY'] = 'secret!' socketio = SocketIO(app) @socketio.on('send_message') def handle_message(data): print('Received message: ' + data['message']) emit('receive_message', {'message': data['message']}, broadcast=True) @app.route('/') def index(): return render_template('index.html') if __name__ == '__main__': socketio.run(app) ``` In my `index.html`, I'm connecting to the SocketIO server like this: ```html <script src="https://cdn.socket.io/4.0.0/socket.io.min.js"></script> <script> var socket = io(); socket.on('connect', function() { console.log('Connected to server'); }); socket.on('receive_message', function(data) { console.log(data.message); }); function sendMessage() { socket.emit('send_message', {'message': 'Hello, World!'}); } </script> <button onclick="sendMessage()">Send Message</button> ``` Previously, clicking the button would successfully emit the message, but now there's no response in the console, and the client doesn't receive any messages. I've checked the network tab and confirmed that the connection is successful, but it seems like the events are not being emitted at all. I tried rolling back Flask to version 1.1.2, and everything worked as expected, but I need to use the latest version for other features. I also looked through the [documentation](https://flask-socketio.readthedocs.io/en/latest/) for breaking changes but couldn't find anything related to event handling. Has anyone else faced similar issues after the upgrade? Any suggestions would be greatly appreciated. Has anyone else encountered this? I'm working in a CentOS environment. Has anyone dealt with something similar? What's the best practice here? My team is using Python for this mobile app. This is part of a larger microservice I'm building. What would be the recommended way to handle this?