NixOS 25.05 (“Warbler”) released — Linux 6.12 LTS, GNOME 48, new tooling and large Nixpkgs refresh

Key update

NixOS 25.05 (codename “Warbler”) is officially released. Highlights for developers: default kernels include Linux 6.12 LTS (with availability of 6.14), GNOME 48, LLVM 19 and GCC 14 updates, a huge Nixpkgs refresh (thousands of package updates/additions), initial support for System76’s COSMIC DE, and an experimental rewrite of the classical nixos-rebuild tooling as nixos-rebuild-ng (Python) available for testing. The release receives maintenance through 2025‑12‑31.

Why it matters

• Toolchain and kernel bump: shipping newer kernels and compilers changes ABI/feature sets and can affect native builds, CI images, Docker base images, kernel modules, and native extension builds (Node native modules, Rust/C/C++ toolchains). Expect reduced need for backported fixes but plan CI/job images that target the new toolchain.
• Big package refresh: thousands of package updates and removals mean dependency versions used to produce reproducible builds can shift; lock and test your Nix flakes/nixpkgs pin before upgrading CI or production systems.
• nixos-rebuild-ng: a tested, opt‑in rewrite of the rebuild workflow opens the door to different automation and scripting ergonomics (and easier contributions). Teams that automate system rebuilds should evaluate it in staging — it’s experimental but significant for long‑term maintenance.
• Upgrade window & EOL: the release lifecycle and deprecation of older images matter for scheduled upgrades in CI and fleet management; pinning strategy and staged rollout testing are advisable to avoid surprises from the large package changes.

Source

• Source