Flask-SocketIO: 解决'Unsupported Socket.IO or Engine.IO protocol' 错误

The error message 'The client is using an unsupported version of the Socket.IO or Engine.IO protocols' indicates that the client-side code is using an incompatible version of Socket.IO or Engine.IO with your server. Here's how to resolve this issue:

1. Update Socket.IO and Engine.IO Libraries:

   • Ensure you have the latest versions of flask-socketio and python-socketio installed. Update them using:

     pip install -U flask-socketio python-socketio
     

2. Check Flask-SocketIO Version:

   • If you're using an older version of flask-socketio (prior to 5.0), you might need to update your socketio.run call. Use:

     socketio.run(app, host='0.0.0.0', port=5000)
     

   • Instead of just socketio.run(app). This ensures the correct host and port are specified for the Socket.IO server.

3. Update Client-Side Socket.IO Library:

   • Locate the Socket.IO client library version in your index.html file. For example:

     <script src='https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.3.1/socket.io.js'></script>
     

   • Update the version number (e.g., 2.3.1) to a compatible version. You can find compatible versions by referring to the Socket.IO documentation and ensuring it matches the server-side version.

4. Restart the Flask Server:

   • After making any changes, restart your Flask server. This ensures the updated libraries and configuration take effect.

Once you've implemented these steps, try running your application again. The error should be resolved, and your client should successfully connect to the Socket.IO server.