Problem

WARNING: httplib2.URLError received None <urlopen error unknown url type: https>

Solution

Access to ECMWF servers is done over HTTPS. Your Python version does not support SSL (Secure Socket Layer) used by HTTPS.

To verify if SSL is enabled in your python , try the following:

>>> import socket
>>> socket.ssl
<function ssl at 0x4038b0>

If the output is not <function ssl at some_hex_number>, then you should rebuild or reinstall Python with ssl enabled.