pip : AttributeError: module ‘lib’ has no attribute ‘Cryptography_HAS_SSL_ST’

So everytime I want to use pip command on Ubuntu 16.04 I get the following error:

 ~ pip3 --version               Traceback (most recent call last):   File "/usr/local/bin/pip3", line 6, in <module>     from pip._internal import main   File "/usr/local/lib/python3.5/dist-packages/pip/_internal/__init__.py", line 40, in <module>     from pip._internal.cli.autocompletion import autocomplete   File "/usr/local/lib/python3.5/dist-packages/pip/_internal/cli/autocompletion.py", line 8, in <module>     from pip._internal.cli.main_parser import create_main_parser   File "/usr/local/lib/python3.5/dist-packages/pip/_internal/cli/main_parser.py", line 12, in <module>     from pip._internal.commands import (   File "/usr/local/lib/python3.5/dist-packages/pip/_internal/commands/__init__.py", line 6, in <module>     from pip._internal.commands.completion import CompletionCommand   File "/usr/local/lib/python3.5/dist-packages/pip/_internal/commands/completion.py", line 6, in <module>     from pip._internal.cli.base_command import Command   File "/usr/local/lib/python3.5/dist-packages/pip/_internal/cli/base_command.py", line 20, in <module>     from pip._internal.download import PipSession   File "/usr/local/lib/python3.5/dist-packages/pip/_internal/download.py", line 15, in <module>     from pip._vendor import requests, six, urllib3   File "/usr/local/lib/python3.5/dist-packages/pip/_vendor/requests/__init__.py", line 97, in <module>     from pip._vendor.urllib3.contrib import pyopenssl   File "/usr/local/lib/python3.5/dist-packages/pip/_vendor/urllib3/contrib/pyopenssl.py", line 46, in <module>     import OpenSSL.SSL   File "/usr/local/lib/python3.5/dist-packages/OpenSSL/__init__.py", line 8, in <module>     from OpenSSL import crypto, SSL   File "/usr/local/lib/python3.5/dist-packages/OpenSSL/SSL.py", line 194, in <module>     if _lib.Cryptography_HAS_SSL_ST: AttributeError: module 'lib' has no attribute 'Cryptography_HAS_SSL_ST' 

I tried to reinstall pyOpenSSL but it requires pip to install it with the command:

pip install pyOpenSSL 

which reproduces the same error message. How can I solve this problem, please?