Python httplib ResponseNotReady

Make sure you don't reuse the same object from a previous connection. You will hit this once the server keep-alive ends and the socket closes.

Previous answers are correct, but there's another case where you could get that exception:

Making multiple requests without reading any intermediate responses completely.

For instance:

conn.request('PUT',...)
conn.request('GET',...)
# will not work: raises ResponseNotReady

conn.request('PUT',...)
r = conn.getresponse()
r.read() # <-- that's the important call!
conn.request('GET',...)
r = conn.getresponse()
r.read() # <-- same thing

and so on.

Additionally, errors like this can occur when the server sends a response without a Content-Length header, which will cripple the state of the HTTP client if Keep-Alive is used and another request is sent over the same socket.

I was running into this same exception today, using this code:

    conn = httplib.HTTPConnection(self._host, self._port)
    conn.putrequest('GET',
        '/retrieve?id={0}'.format(parsed_store_response['id']))
    retr_response = conn.getresponse()

I didn't notice that I was using putrequest rather than request; I was mixing my interfaces. ResponseNotReady is raised because I haven't actually sent the request yet.