uv 0.12.20

on Python PyPI

Release Notes

Released on 2026-09-28.

Enhancements

• Reuse lockfiles when dependency declarations are semantically equivalent (#21951)
• Preserve second-line encoding declarations when installing wheel scripts with CRLF shebangs (#21990)

Preview features

• Write normalized requirement declarations with the lockfile-normalization preview feature (#21951)
• Honor synthetic default groups when installing or syncing from pylock.toml (#22003)
• Resolve local paths in exported pylock.toml files relative to the output file (#22042)
• Install each package only once when repeated tool-install-locks requirements resolve to the same package (#22000)
• Reuse lock-without-metadata lockfiles for conflicting groups with distinct base and extra requirement specifiers (#22055)
• Use consistent root-package paths in uv workspace metadata and uv tree --format json output (#22050)

Configuration

• Continue searching XDG_CONFIG_DIRS after empty entries (#21987)

Performance

• Restore the previous HTTP cache-write scheduling while investigating severe cache-revalidation stalls on ext4 filesystems (#22051)

Bug fixes

• Apply hash constraints to every repeated requirement under --require-hashes and --verify-hashes (#21996)
• Allow metadata builds for first-party workspace projects under --no-build (#21988)
• Honor project exclusion flags with --all-packages, including --no-install-project and --no-emit-project (#21994)
• Restore pyproject.toml if uv upgrade fails or is interrupted (#21983)
• Generate working Nushell activation scripts for relocatable virtual environments (#21979)
• Prevent commands from running and changing state after displaying --show-settings (#21989)
• Treat UTF-16 requirements files containing only a byte-order mark as empty (#21991)
• Ignore unrecognized managed-Python implementation directories during uv python list and uv python upgrade instead of panicking (#22033)
• Avoid panics and incorrect rewriting when managed Python sysconfig paths merely start with /install (#22036)
• Report whitespace-only non-ASCII requirements as invalid instead of panicking (#22035)
• Avoid a resolver panic when trace logging an always-false constraint (#22034)

Install uv 0.12.20

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://releases.astral.sh/github/uv/releases/download/0.12.20/uv-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://releases.astral.sh/github/uv/releases/download/0.12.20/uv-installer.ps1 | iex"

Download uv 0.12.20

Verifying GitHub Artifact Attestations

The artifacts in this release have attestations generated with GitHub Artifact Attestations. These can be verified by using the GitHub CLI:

gh attestation verify <file-path of downloaded artifact> --repo astral-sh/uv

You can also download the attestation from GitHub and verify against that directly:

gh attestation verify <file-path of downloaded artifact> --bundle <file-path of downloaded attestation>