JSONDecodeError "Expecting value" From None When Trying to Connect

[esot0]

Hey everyone, running this with gevent here. My socket seems to never connect to the backend, and this is the error message I get when it does:
Error logs from backend:

yL-6q014xsYpkJ1kAAAA: Sending packet OPEN data {'sid': 'yL-6q014xsYpkJ1kAAAA', 'upgrades': ['websocket'], 'pingTimeout': 20000, 'pingInterval': 25000}
yL-6q014xsYpkJ1kAAAA: Received packet MESSAGE data 0:5000,
message handler error
Traceback (most recent call last):
  File "/home/emily/anaconda3/lib/python3.8/site-packages/engineio/server.py", line 603, in _trigger_event
    return self.handlers[event](*args)
  File "/home/emily/anaconda3/lib/python3.8/site-packages/socketio/server.py", line 740, in _handle_eio_message
    pkt = packet.Packet(encoded_packet=data)
  File "/home/emily/anaconda3/lib/python3.8/site-packages/socketio/packet.py", line 40, in __init__
    self.attachment_count = self.decode(encoded_packet)
  File "/home/emily/anaconda3/lib/python3.8/site-packages/socketio/packet.py", line 111, in decode
    self.data = self.json.loads(ep)
  File "/home/emily/anaconda3/lib/python3.8/site-packages/engineio/json.py", line 16, in loads
    return original_loads(*args, **kwargs)
  File "/home/emily/anaconda3/lib/python3.8/json/__init__.py", line 370, in loads
    return cls(**kw).decode(s)
  File "/home/emily/anaconda3/lib/python3.8/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/home/emily/anaconda3/lib/python3.8/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None

I'm not quite sure what's going on, since I'm a little lost on any malformed json I might be sending.
Output from frontend when I send a message:

Object { receiveBuffer: [], sendBuffer: (1) […], ids: 0, acks: {}, flags: {}, io: {…}, nsp: ":5000", connected: false, disconnected: true, subs: (4) […]}
Chat.js:156

And here's my relevant frontend code:

Connecting:

import React from 'react'
import io from 'socket.io-client'
import { SITE_ROOT } from '../utility';
export const socket = io.connect(`${SITE_ROOT}:5000`)
export const SocketContext = React.createContext();

Chat:

	const socket = useContext(SocketContext);
	const handleReceiveMessage = useCallback((msg) => {
		console.log("Handling received msg...")
		const id = jwt.id.replace(/['"]+/g, '');
		if (id == msg.recipient.$oid) {
			set_messages((previous_messages) => {
				const newArr = [...previous_messages.messages, msg]
				return {
					offset: previous_messages.offset,
					recipient: previous_messages.recipient,
					displayed: (previous_messages.offset + perPage >= newArr.length ? newArr.slice(previous_messages.offset, newArr.length) : newArr.slice(previous_messages.offset, previous_messages.offset + perPage)),
					messages: newArr
				}
			})

		}
	}, [])

	useEffect(() => {
	/*setup*/
		socket.on("msg", handleReceiveMessage)
		return () => {
			socket.disconnect();
		};
	}, [])

	/* bunch of stuff */
        	//axios request
			.then((res) => {
				socket.emit("msg", res)
				console.log("Sent out a message")
				console.log(socket)
			})

Server:

from gevent import monkey
monkey.patch_all()
  socketio = SocketIO(app, logger=True, engineio_logger=True, cors_allowed_origins=["http://localhost:3000"])
@socketio.on('msg')
def handle_message(msg):
    print("Got a msg")
    socketio.emit('msg', msg)  

@socketio.on('connect')
def connect():
    print("Connected to server") 

if __name__ == '__main__':
    port = int(os.environ.get('PORT'))
    socketio.run(app=app, use_reloader=True, port=port, debug=True)

Thank you for any help you can provide!

[miguelgrinberg]

What is the value of your SITE_ROOT variable? I think the part where you attach :5000 to it might be generating an invalid URL.

[esot0]

That was it, thank you so much!