File "/bin/certbot", line 7, in
from certbot.main import main
File "/usr/lib/python2.7/site-packages/certbot/main.py", line 17, in
from certbot import client
File "/usr/lib/python2.7/site-packages/certbot/client.py", line 10, in
from acme import client as acme_client
File "/usr/lib/python2.7/site-packages/acme/client.py", line 31, in
requests.packages.urllib3.contrib.pyopenssl.inject_into_urllib3() # type: ignore
File "/usr/lib/python2.7/site-packages/requests/packages/urllib3/contrib/pyopenssl.py", line 112, in inject_into_urllib3
_validate_dependencies_met()
File "/usr/lib/python2.7/site-packages/requests/packages/urllib3/contrib/pyopenssl.py", line 147, in _validate_dependencies_met
raise ImportError("'pyOpenSSL' module missing required functionality. "
ImportError: 'pyOpenSSL' module missing required functionality. Try upgrading to v0.14 or newer.

Solution

Compare versions

pip list 2>/dev/null | grep requests

requests                         1.3.0
requests-toolbelt                0.8.0

rpm -q python-requests --queryformat '%{VERSION}\n'

2.6.0

If they're different, try

pip install --upgrade --force-reinstall 'requests==2.6.0'

Certbot ImportError: ‘pyOpenSSL’ module missing required functionality. Try upgrading to v0.14 or newer.