1error:2 … while evaluating the attribute 'optionalValue.value'3 at «github:NixOS/nixpkgs/a47c123a609287a012dfc44d281de2dd4ed13394?narHash=sha256-IpX7tmVJi9seHg5M4Wuexy78bQDlbntVk1HcT9kFts4%3D»/lib/modules.nix:1312:5:4 1311|5 1312| optionalValue = if isDefined then { value = mergedValue; } else { };6 | ^7 1313| };89 … while evaluating a branch condition10 at «github:NixOS/nixpkgs/a47c123a609287a012dfc44d281de2dd4ed13394?narHash=sha256-IpX7tmVJi9seHg5M4Wuexy78bQDlbntVk1HcT9kFts4%3D»/lib/modules.nix:1312:21:11 1311|12 1312| optionalValue = if isDefined then { value = mergedValue; } else { };13 | ^14 1313| };1516 … while evaluating definitions from `/nix/store/hqh4dp94r41rk0k4b9b6v804nrlwmij8-source/modules/transposition.nix':1718 … while evaluating the option `perSystem.aarch64-linux.checks':1920 … while evaluating definitions from `/nix/store/9c0qvgjs572xqab9212a3pw51nwnlmxx-source/flake.nix, via option perSystem':2122 … while evaluating the module argument `self'' in ":anon-12:anon-1":2324 … noting that argument `self'` is not externally provided, so querying `_module.args` instead, requiring `config`2526 … while evaluating definitions from `/nix/store/hqh4dp94r41rk0k4b9b6v804nrlwmij8-source/modules/perSystem.nix':2728 … while retrieving system-dependent attributes for a flake's own outputs2930 … while evaluating definitions from `/nix/store/hqh4dp94r41rk0k4b9b6v804nrlwmij8-source/modules/formatter.nix':3132 … while evaluating the option `flake.formatter':3334 … while evaluating definitions from `/nix/store/hqh4dp94r41rk0k4b9b6v804nrlwmij8-source/modules/formatter.nix':3536 … while evaluating the option `perSystem.x86_64-darwin.formatter':3738 … while evaluating the option `perSystem.x86_64-darwin.treefmt.build.wrapper':3940 … while evaluating the module argument `pkgs' in "/nix/store/1vl291j7zmnqw700hyj840j9yqv94plk-source/module-options.nix":4142 … noting that argument `pkgs` is not externally provided, so querying `_module.args` instead, requiring `config`4344 … while evaluating definitions from `/nix/store/1vl291j7zmnqw700hyj840j9yqv94plk-source/flake-module.nix':4546 … while evaluating the option `perSystem.x86_64-darwin.treefmt.pkgs':4748 … while evaluating the module argument `pkgs' in ":anon-10:anon-1":4950 … noting that argument `pkgs` is not externally provided, so querying `_module.args` instead, requiring `config`5152 … while evaluating definitions from `/nix/store/hqh4dp94r41rk0k4b9b6v804nrlwmij8-source/modules/transposition.nix':5354 (stack trace truncated; use '--show-trace' to show the full, detailed trace)5556 error: Nixpkgs 26.11 has dropped support for x86_64-darwin.5758 The 26.05 stable branch still supports x86_64-darwin, and will59 receive security fixes until the end of 2026. If you use channels,60 you can switch to 26.05 as follows:6162 $ sudo nix-channel --add https://nixos.org/channels/nixpkgs-26.05-darwin nixpkgs63 $ sudo nix-channel --update6465 If this doesn’t work, you may need to run:6667 # Lack of sudo is deliberate:68 $ nix-channel --remove nixpkgs6970 If you use flakes, switch your flake input:7172 inputs.nixpkgs = {73 url = "github:NixOS/nixpkgs/nixpkgs-26.05-darwin";74 };7576 See the release notes for more information and alternatives:7778 https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.11