I faced the same issue because the Webchat widget is not compatible with the latest version of Rasa. Additionally, Rasa needs to be compatible with the Socket.IO client version. To resolve this, I build a custom frontend using a compatible version of Socket.IO for a stable connection. I also modify the line sio.enter_room(sid, data["session_id"]) in venv/lib/python3.8/site-packages/rasa/core/channels/socketio.py to await sio.enter_room(sid, data["session_id"]), and it works.