(on behalf of RMs, this was coordinated and drafted beforehand) The user experience of non-flakes 2.4 is a great concern and there are enough regressions in behavior to make us reconsider. The reports of breakages are useful and helps Nix developers prioritize fixes. This will also give the new experimental features a chance to mature prior to the the next 22.05 release. Our current preference is to revert the default Nix version to 2.3 ONLY for the 21.11 release which will show up as nixos-21.11, nixos-21.11-small, and nixpkgs-21.11-darwin. Users of nixpkgs-unstable, nixos-unstable, and nixos-unstable-small branches will continue to use Nix2.4 as default. The community benefits from testing by users who deploy with various combinations of old/new client/daemon or complex setups. Please send in reports and make issues! The reports of breakages from users provide valuable feedback and provide the right kind of pressure for continued development.
This actual proposed fix will likely be something this simple and something in the release notes.
diff --git a/pkgs/tools/package-management/nix/default.nix b/pkgs/tools/package-management/nix/default.nix
index f365348607a..463ebe49f3d 100644
--- a/pkgs/tools/package-management/nix/default.nix
+++ b/pkgs/tools/package-management/nix/default.nix
@@ -220,7 +220,7 @@ in rec {
nix = nixStable;
- nixStable = nix_2_4;
+ nixStable = nix_2_3;
nix_2_3 = callPackage common (rec {
pname = "nix";