1error:2 … while evaluating the attribute 'optionalValue.value'3 at «git+https://github.com/NixOS/nixpkgs?ref=nixpkgs-unstable&rev=b471514bed69eff5255c8e63c1f80e5fe56c616f&shallow=1»/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 «git+https://github.com/NixOS/nixpkgs?ref=nixpkgs-unstable&rev=b471514bed69eff5255c8e63c1f80e5fe56c616f&shallow=1»/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/ch5n4xdddid5859dy6c4i6lghqyx8016-source/modules/transposition.nix':1718 … while evaluating the option `perSystem.x86_64-darwin.checks':1920 … while evaluating definitions from `/nix/store/rqiwcnrf5injjsqyv4vj9lpbrbq8y5i7-source/flake.nix, via option perSystem':2122 … while evaluating the module argument `pkgs' in ":anon-12:anon-1":2324 … noting that argument `pkgs` is not externally provided, so querying `_module.args` instead, requiring `config`2526 … while evaluating definitions from `/nix/store/ch5n4xdddid5859dy6c4i6lghqyx8016-source/modules/transposition.nix':2728 (stack trace truncated; use '--show-trace' to show the full, detailed trace)2930 error: Nixpkgs 26.11 has dropped support for x86_64-darwin.3132 The 26.05 stable branch still supports x86_64-darwin, and will33 receive security fixes until the end of 2026. If you use channels,34 you can switch to 26.05 as follows:3536 $ sudo nix-channel --add https://nixos.org/channels/nixpkgs-26.05-darwin nixpkgs37 $ sudo nix-channel --update3839 If this doesn’t work, you may need to run:4041 # Lack of sudo is deliberate:42 $ nix-channel --remove nixpkgs4344 If you use flakes, switch your flake input:4546 inputs.nixpkgs = {47 url = "github:NixOS/nixpkgs/nixpkgs-26.05-darwin";48 };4950 See the release notes for more information and alternatives:5152 https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.11