BACKWARDS INCOMPATIBLE: Removed support for passing an Extension instance to from_issuer_subject_key_identifier() , as per our deprecation policy.

BACKWARDS INCOMPATIBLE: Support for LibreSSL 2.7.x, 2.8.x, and 2.9.0 has been removed (2.9.1+ is still supported).

BACKWARDS INCOMPATIBLE: Dropped support for macOS 10.9, macOS users must upgrade to 10.10 or newer.

BACKWARDS INCOMPATIBLE: RSA generate_private_key() no longer accepts public_exponent values except 65537 and 3 (the latter for legacy purposes).

BACKWARDS INCOMPATIBLE: X.509 certificate parsing now enforces that the version field contains a valid value, rather than deferring this check until version is accessed.

Deprecated support for Python 2. At the time there is no time table for actually dropping support, however we strongly encourage all users to upgrade their Python, as Python 2 no longer receives support from the Python core team.

If you have trouble suppressing this warning in tests view the FAQ entry addressing this issue.