QIODevice::read (QTcpSocket): device not open

根据提供的引用内容，这个问题可能是由于在使用QIODevice::read函数时，QTcpSocket没有正确打开导致的。可以尝试在使用read函数之前，先使用open函数打开QTcpSocket。具体的代码实现可以参考以下范例：

import socket

# 创建一个TCP/IP套接字
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 连接到远程套接字
server_address = ('localhost', 10000)
print('connecting to {} port {}'.format(*server_address))
sock.connect(server_address)

# 打开套接字
sock.open(QIODevice.ReadWrite)

# 发送数据
message = 'This is the message. It will be repeated.'
print('sending {!r}'.format(message))
sock.sendall(message.encode('utf-8'))

# 接收数据
amount_received = 0
amount_expected = len(message)

while amount_received < amount_expected:
    data = sock.read(16)
    amount_received += len(data)
    print('received {!r}'.format(data))

# 关闭套接字
print('closing socket')
sock.close()