如何解决ConnectionRefusedError：[Errno 111]连接被拒绝

Question

使用一些代码并得到以下错误：

File "/usr/lib/python3.6/http/client.py", line 974, in send
self.connect()
File "/usr/lib/python3.6/http/client.py", line 946, in connect
(self.host,self.port), self.timeout, self.source_address)
File "/usr/lib/python3.6/socket.py", line 724, in 
create_connection
raise err
File "/usr/lib/python3.6/socket.py", line 713, in 
create_connection
sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

我该如何解决？