Supported Python Versions

The versions of Python supported by Mercurial.

1. Current support

Mercurial 4.3 and newer require Python 2.7. Mercurial versions up to 4.2 support Python versions 2.6 to 2.7, provided they include the following standard library components:

• sha/hashlib
• gzip
• bz2 (needed for bundles)
• ctypes (only on Windows)

Mercurial 3.5 dropped support for Python 2.4 and 2.5. As our primary users of these Python versions are enterprise Linux users of RHEL 5 and Centos 5, we've started packaging RPMs for these systems with a private copy of a recent Python.

Mercurial 4.3 dropped support for Python 2.6. As work towards porting to Python 3 progressed, continuing to support Python 2.6 was a hindrance to porting efforts.

Some versions of Python may have difficulty with some particular features. For instance, Python before 2.5 cannot properly verify SSL certificates.

2. Future support plan

Python 2.3 support was dropped in July 2009 for Mercurial 1.3 when it became difficult for developers to continue testing compatibility. Now that we have a 2.4 buildbot, this is mostly a non-issue.

Python 2.4 and 2.5 support was dropped in May 2015 for Mercurial 3.5 as it was becoming a barrier to Python 3.x support.

We may drop support for Python 2.7 sometime in 2020. See Python3 for more information.

3. Python 3.x support

Mercurial 5.2 and newer has support for Python 3.5 and newer.

Mercurial will never support Python 3.0 to 3.4 because of missing support for the % operator on bytestrings (bytes in Python 3).