Trouble Sending integer over Socket Server

Question

When trying to send and decode an integer using socketserver and port, I get the following error ValueError: invalid literal for int() with base 10: '' (full stack trace at end). I marked the place where the error is with #<----- in the client. Note that I've tried all of the following: Increasing the buffer size, sending it as a string, trying every caste I could think of (to string then int, to float, to int before sending it, to byte then to int, etc.) though I may have missed one.

This is the code for my server:

import socketserver
import threading
import gameplayer


class GameServer:
    class GameServerUDPHandler(socketserver.BaseRequestHandler):
        def handle_register(self, socket, client_address):
            number = len(self.server.base.players)  # Zero based
            number = number + 1  # One based
            socket.sendto(bytes(number), client_address)
            self.server.base.players[number] = gameplayer.GamePlayer(id=number)
            print(self.server.base.players)

        def handle(self):
            data = self.request[0].strip()
            data = str(data, 'utf-8')
            print(data)
            socket = self.request[1]
            data = data.split('\n')
            option = data[0]
            print(option)
            c_add = self.client_address
            if option == "register":
                self.handle_register(socket, c_add)
                print("test")
            elif option == "get_postion":
                handle_get_postion(socket, c_add, data[1])
            elif option == "change_postion":
                hande_changed_postion(socket, c_add, data[1])
            # print("{} wrote:".format(self.client_address[0]))
            # socket.sendto(data.upper(), self.client_address)

    def __init__(self, port):
        self.server = socketserver.UDPServer(("localhost", port), self.GameServerUDPHandler)
        self.server.base = self
        self.players = {}

    def start_server(self):
        threading.Thread(target=self.server.serve_forever).start()

And my client (where the error is):

class GameClient:
    def __init__(self, port, host):
        self.port = port
        self.host = host
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    def register(self):
        self.socket.sendto(bytes("register\n", "utf-8"), (self.host, self.port))
        self.numberID = int(self.socket.recv(10240).strip()) #<- WHERE ISSUE IS
        print("Received:   {}".format(self.numberID))

Full Output (Error starts at part marked):

register
register
{1: <gameplayer.GamePlayer object at 0x10078e390>}
test
Traceback (most recent call last): #<---- Where the error starts in the output.
  File "main.py", line 8, in <module>
    client.register()
  File "/Users/Mike/Desktop/Main/Programming/Work Space/Python/Game/gameclient.py", line 12, in register
    self.numberID = int(self.socket.recv(10240))
ValueError: invalid literal for int() with base 10: ''

Answer 1

Change following line in the server code:

socket.sendto(bytes(number), client_address)

with:

socket.sendto(str(number).encode('utf-8'), client_address)

---

>>> bytes(3)
b'\x00\x00\x00'
>>> str(3)
'3'
>>> str(3).encode('utf')
b'3'

And the cause of the traceback

>>> int(bytes(3))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: ''