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Release Cadence

Overview

NixOS ships a new stable release about twice a year. RFC 0080 moved the targets from March/September to May and November (first applied by delaying 21.03 → 21.05); since then names follow YY.05 and YY.11 (for example 26.05, 25.11). Each stable line gets its own channel (nixos-26.05, …) that takes conservative fixes until the next stable branch takes over. The NixOS Release Team runs the cut from roadmap through artifacts.

That cadence is not the same as Nix (the evaluator/daemon) versioning. NixOS and Nixpkgs advance on the six-month schedule above; the Nix package manager has its own release notes and version numbers (the download page lists them separately). A NixOS release may bump the packaged Nix, but you track Nix CLI/experimental-feature changes separately from “which NixOS stable am I on?”

Day to day, most installs follow a channel rather than a calendar date: stable lines vs nixos-unstable / nixpkgs-unstable. Live channel health is on status.nixos.org; channel URLs live at channels.nixos.org.

When refreshing this wiki after a release, follow meta/release-checklist.md.

Current illustrative stable (last checked 2026-07-31): the NixOS download page listed NixOS 26.05 as current; nixos-26.05 and the prior line nixos-25.11 both resolve on channels.nixos.org. Re-check those pages before treating any YY.MM as “latest.”

Details

Stable release line. Roughly every six months, Nixpkgs branches a release-YY.MM line and publishes a matching nixos-YY.MM channel. Stable channels receive bug and security updates, not wholesale desktop or ABI churn. The previous stable is typically maintained until the next one is established; check the current supported stable on the download page and channels.nixos.org.

Unstable. nixos-unstable (and nixpkgs-unstable for non-NixOS Nixpkgs users) tracks main development after Hydra tests pass. Updates are rolling: channel bumps can include large package or module changes. Unstable is the cutting edge, not a second “LTS.”

Small channels. Names like nixos-26.05-small or nixos-unstable-small use the same sources with a smaller binary set, so they advance faster but may force more local builds—common for servers.

Channel advancement vs calendar release. Cutting YY.05 / YY.11 is a discrete event (branch-off, ZHF, announcement). After that, the channel for that line still moves whenever Hydra’s tested job succeeds. status.nixos.org shows last update, commit, and whether a channel is progressing.

Nix vs NixOS versions. Upgrading NixOS channels can pull a newer Nix when the release packages one; Nix’s own major/minor releases and experimental-feature stabilization follow Nix release notes, not the NixOS YY.MM label. See tracking stabilization for how Nix flags land and stabilize across Nix releases. Which binary you run (CppNix, Lix, …) is a separate choice from which NixOS channel you follow.

Flakes. Flake-based systems pin nixpkgs (or a flake input) to a revision or branch instead of (or in addition to) classic channels. The same release-YY.MM / nixos-unstable lines exist as Git branches; the twice-yearly cadence still describes when stable branches appear.

Examples

  • Current stable channel (illustrative): subscribe root to the line matching your install, e.g. nixos-26.05:
# as root — replace YY.MM with the release you want
nix-channel --add https://channels.nixos.org/nixos-26.05 nixos
nixos-rebuild switch --upgrade

  • Unstable: nix-channel --add https://channels.nixos.org/nixos-unstable nixos then rebuild with --upgrade. Prefer stable for production; see upgrades.

  • Check channel progress: open status.nixos.org for last-updated times and Hydra job status; browse channels.nixos.org for available channel names and redirects to the current snapshot.

References

See also

  • Timeline — historical milestones in the Nix ecosystem
  • Upgrades — day-to-day channel upgrades on NixOS
  • Channel — what a channel is and how subscriptions work
  • Tracking stabilization — Nix feature flags across Nix releases (separate from NixOS YY.MM)
  • CppNix — reference Nix implementation often packaged by NixOS