问在连接客户端之后，服务器上出现错误"concurrent.futures._base.CancelledError“

EN

#!/usr/bin/env python3

# WS server example

import asyncio
import websockets

#======================================================================
#Register
#======================================================================
async def Register(websocket):
    remote_ip = websocket.remote_address[0] #Get client IP
    print ("IP: " + remote_ip)
    message="Hi. Your IP: " +remote_ip
    await websocket.send(message) #Say client IP
    print("==> " + str(message))

#======================================================================
#Handler
#======================================================================    
async def Handler(websocket, path):
    print("Client connect!")
    await Register(websocket)

    #try:
    async for message in websocket:
        print("<== " + str(message))

        await websocket.send(message)
        print("==> " + str(message))

    #except Exception as E:
        #print(str(E))
    #finally:
        #await asyncio.sleep(2)

#======================================================================
#MAIN
#======================================================================
print("Starting!")
start_server = websockets.serve(Handler, "0.0.0.0", 8012)
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()

Error in connection handler
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 827, in transfer_data
    message = await self.read_message()
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 895, in read_message
    frame = await self.read_data_frame(max_size=self.max_size)
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 971, in read_data_frame
    frame = await self.read_frame(max_size)
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 1051, in read_frame
    extensions=self.extensions,
  File "/usr/local/lib/python3.7/site-packages/websockets/framing.py", line 105, in read
    data = await reader(2)
  File "/usr/local/lib/python3.7/asyncio/streams.py", line 679, in readexactly
    await self._wait_for_data('readexactly')
  File "/usr/local/lib/python3.7/asyncio/streams.py", line 473, in _wait_for_data
    await self._waiter
concurrent.futures._base.CancelledError

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/websockets/server.py", line 191, in handler
    await self.ws_handler(self, path)
  File "StartWB3.py", line 26, in Handler
    async for message in websocket:
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 439, in __aiter__
    yield await self.recv()
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 509, in recv
    await self.ensure_open()
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 812, in ensure_open
    raise self.connection_closed_exc()
websockets.exceptions.ConnectionClosedError: code = 1006 (connection closed abnormally [internal]), no reason