1. Migrate from pyenv to mise: Complete Guide for Python 3.12 to 3.13 Upgrades

Migrating from pyenv to mise streamlines Python version management. Mise, a Rust-based tool, replaces pyenv with faster shims, multi-language support, tasks, and direnv-like environments. This guide covers uninstalling pyenv, installing mise, migrating configs, and upgrading to Python 3.13.

Why Migrate from pyenv to mise?

Pyenv is Python-specific and uses slow shell shims. Mise offers:

• Speed: Rust implementation, blazing-fast.
• Versatility: Manages Node, Go, Rust, etc.
• Environments: Automatic env vars per project.
• Tasks: Built-in task runner like Make.
• Python 3.13 Support: Latest versions readily available.

Perfect for Python 3.12 to 3.13 upgrades amid new features like improved error messages.

Prerequisites

• macOS/Linux (Windows via WSL).
• Homebrew (optional).
• Backup .python-version files.

Step 1: Uninstall pyenv

Remove pyenv completely:

# If installed via Homebrew
brew uninstall pyenv pyenv-virtualenv

# Remove pyenv directory
rm -rf ~/.pyenv

# Edit shell config (~/.zshrc, ~/.bashrc)
# Remove lines like:
# export PYENV_ROOT="$HOME/.pyenv"
# export PATH="$PYENV_ROOT/bin:$PATH"
# eval "$(pyenv init -)"

Restart shell: exec $SHELL

Step 2: Install mise

curl https://mise.run | sh

Add to shell (e.g., ~/.zshrc):

echo 'eval "$(mise activate zsh)"' >> ~/.zshrc
exec $SHELL

Verify: mise --version

Step 3: Migrate Python Versions from pyenv

List pyenv versions (if remnants):

# From backup or memory, e.g., 3.12.5

Install with mise:

mise use --global python@3.12
mise use python@3.13.0  # Latest 3.13

Step 4: Update Config Files

Rename .python-version to .tool-versions:

mv .python-version .tool-versions

Mise reads .tool-versions for python=node etc.

Step 5: Verify Migration

python --version  # Should show 3.13.0
pip --version
which python      # ~/.local/share/mise/installs/python/3.13.0/bin/python

Test project: mise run test (if tasks defined).

Upgrading Projects to Python 3.13

1. cd project
2. Edit .tool-versions: python 3.13.0
3. mise install
4. Update deps: pip install --upgrade pip
5. Test: Run your tests.

Handle breaking changes: Check Python 3.13 What’s New.

Troubleshooting

• Shims not working: mise doctor
• Install fails: Set MISE_GITHUB_TOKEN for rate limits.
• Shell not activated: Restart or source ~/.zshrc.

Conclusion

You’ve migrated from pyenv to mise and upgraded to Python 3.13. Enjoy faster workflows! Share experiences in comments. Explore mise docs for more.