Certbot 0.40.1 has been released. The changelog entry for the release is:
0.40.1 - 2019-11-05
- Added back support for Python 3.4 to Certbot components and certbot-auto due
to a bug when requiring Python 2.7 or 3.5+ on RHEL 6 based systems.
More details about these changes can be found on our GitHub repo.