I have searched on the web for over two days now, and probably have looked through most of the online documented scenarios and workarounds, but nothing worked for me so far.
In my case (python) it failed because I had these two lines of code in the file, inherited from an older code
http.client.HTTPConnection._http_vsn = 10 http.client.HTTPConnection._http_vsn_str = 'HTTP/1.0'