Drop Python

Dropping Python Support

This guide provides step-by-step instructions for removing a Python support from a project. If the user doesn't specify a version, assume the lowest supported version is being bumped by one. Always drop one Python version at a time.

Below, ` is used instead of a specific digit; if dropping 3.9, then ` is 9.

Before You Start

• uv is required, quit if they are not installed. You can run any

other project-specific tools via uvx, such as nox -> uvx nox and prek -> uvx prek if they are not present.

• prek is a faster Rust rewrite of pre-commit with the same config and

similar options. prek -a --quiet is best for running it.

Key Steps

1. Update pyproject.toml (or setup.cfg or setup.py)

Update Python version classifiers and requirements with the new minimum version. For example, if dropping Python 3.9:

[project]
requires-python = ">=3.10"
classifiers = [
    "Programming Language :: Python :: 3",
    # Remove "Programming Language :: Python :: 3.9",
    "Programming Language :: Python :: 3.10",
    # ...
]

2. Update CI/CD Configuration

If the next version is already tested, drop it. If not, update from the old to the new.

• GitHub Actions (.github/workflow/*.yml)
• Other common CI systems

3. Update Pre-commit Hooks

Check .pre-commit-config.yaml for anything pinned to to the old version.

4. Update other configuration

Some tools also pin in pyproject.toml. Check for 3. and 3 text. Some common locations:

• ruff: Usually Ruff reads project.requires-python, but if it's hardcoded, it's tool.ruff.target-version in pyproject.toml or ruff.target-version in ruff.toml or .ruff.toml
• mypy: tool.mypy.python_version
• pylint: tool.pylint.py-version (can also be tool.pylint.master.py-version (deprecated) or tool.pylint.main.py-version)

5. If cibuildwheel is used

Check for usage of cp3 / pp3 in [tool.cibuildwheel]` as well as in the CI.

6. Run Automated Upgrades

prek -a --quiet

7. Review & Modernize Code

Custom patterns to look for, for specific versions of Python are provided:

• Python 3.7: Read resources/python-37.md
• Python 3.8: Read resources/python-38.md
• Python 3.9: Read resources/python-39.md
• Python 3.10: Read resources/python-310.md
• Python 3.11: Read resources/python-311.md
• Python 3.12: Read resources/python-312.md
• Python 3.13: Read resources/python-313.md
• Python 3.14: Read resources/python-314.md

8. Update Documentation

• Update README, CONTRIBUTING, and docs
• Update installation requirements

9. Test & Validate

If the project has::

[dependency-groups]
dev = # ...

Then run:

uv run pytest

Otherwise check for nox or tox, and run that.

10. Double-check for Remaining References

# Search for 3. references
git grep "\b3\.\b"
git grep "\bpy3\b"
git grep "3, "

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: henryiii
• Source: henryiii/skills
• License: MIT

Install and usage instructions live in the source repository linked above.