uv 0.12.4

uv 0.12.4, released on August 13, 2026, delivers performance improvements to the resolver, new preview features for uv check, and a focused set of bug fixes. This release continues the Astral team's push to make Python package management faster and more correct.

Enhancements

• TLS connections now prefer post-quantum key exchange, with opt-in TLS diagnostics available for debugging
• Whitespace before versions is accepted in noncompliant wildcard comparisons such as Requires-Python: >= 3.5.*
• A specific error is reported when a PEP 723 closing tag contains trailing whitespace or other content
• Source-span carets are omitted from diagnostics for empty PEP 508 requirements

Preview Features

• uv check gains --no-install-project, plus the UV_NO_INSTALL_PROJECT environment variable, to install dependencies without building or installing the project
• The ty subprocess invoked by uv check now honors uv's color and progress settings, including quiet mode

Performance

Resolutions with long runs of unavailable package versions are faster thanks to coalescing gaps in the resolver's version ranges, and Simple API parsing is sped up by deserializing PyPI and Pyx file metadata directly.

Bug Fixes

• Virtual environments created from managed Python minor-version links now use windowed pythonw.exe launchers on Windows
• uv lock proceeds even when .venv is an unusable project environment
• Fork-strategy is respected when ordering forks created from environments or existing lockfile resolution markers
• Consecutive wildcard minor-version exclusions (such as !=3.11.*, !=3.12.*) are preserved in uv.lock
• Interpreter cache reuse is prevented across different PYTHONEXECUTABLE and __PYVENV_LAUNCHER__ overrides
• Inline comments on the final item in dependency arrays are preserved when uv add updates them

Upgrade

Install uv 0.12.4 via the installer script, or run uv self update if you are already on a recent version. The release ships prebuilt binaries for macOS, Windows, and Linux across x86_64, ARM64, and more, all with GitHub Artifact Attestations for verification.