1error:2 … while evaluating the attribute 'optionalValue.value'3 at «github:NixOS/nixpkgs/767b0d3ec98a143ad9ed7dfc0d5553510ac27133?narHash=sha256-tzMgSkV7kljEkqIjlgV6F%2Bn%2BxD%2B/a35Db8bs7a4BFAo%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/767b0d3ec98a143ad9ed7dfc0d5553510ac27133?narHash=sha256-tzMgSkV7kljEkqIjlgV6F%2Bn%2BxD%2B/a35Db8bs7a4BFAo%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/xfg4bws749i95jvnxhymxmfwailzk38q-source/modules/transposition.nix':1718 … while evaluating the option `perSystem.x86_64-darwin.checks':1920 … while evaluating definitions from `/nix/store/i62xwbmwbjdwc4i67ixasbxdy2pba5xz-source/flake.nix, via option perSystem':2122 … while evaluating the option `perSystem.x86_64-darwin.packages':2324 … while evaluating definitions from `/nix/store/i62xwbmwbjdwc4i67ixasbxdy2pba5xz-source/flake.nix, via option perSystem':2526 … while evaluating the module argument `pkgs' in ":anon-12:anon-1":2728 … noting that argument `pkgs` is not externally provided, so querying `_module.args` instead, requiring `config`2930 … while evaluating definitions from `/nix/store/xfg4bws749i95jvnxhymxmfwailzk38q-source/modules/transposition.nix':3132 (stack trace truncated; use '--show-trace' to show the full, detailed trace)3334 error: Nixpkgs 26.11 has dropped support for x86_64-darwin.3536 The 26.05 stable branch still supports x86_64-darwin, and will37 receive security fixes until the end of 2026. If you use channels,38 you can switch to 26.05 as follows:3940 $ sudo nix-channel --add https://nixos.org/channels/nixpkgs-26.05-darwin nixpkgs41 $ sudo nix-channel --update4243 If this doesn’t work, you may need to run:4445 # Lack of sudo is deliberate:46 $ nix-channel --remove nixpkgs4748 If you use flakes, switch your flake input:4950 inputs.nixpkgs = {51 url = "github:NixOS/nixpkgs/nixpkgs-26.05-darwin";52 };5354 See the release notes for more information and alternatives:5556 https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.11