1error:2 … while evaluating the attribute 'optionalValue.value'3 at «github:nix-community/nixpkgs.lib/db3f255737b94216eb71cce308e2912cf6bc2d7c?narHash=sha256-ePjCwr1sNm9NYUqywL7QfK3JnlS015msC%2BeBu2zKlp8%3D»/lib/modules.nix:1310:5:4 1309|5 1310| optionalValue = if isDefined then { value = mergedValue; } else { };6 | ^7 1311| };89 … while evaluating a branch condition10 at «github:nix-community/nixpkgs.lib/db3f255737b94216eb71cce308e2912cf6bc2d7c?narHash=sha256-ePjCwr1sNm9NYUqywL7QfK3JnlS015msC%2BeBu2zKlp8%3D»/lib/modules.nix:1310:21:11 1309|12 1310| optionalValue = if isDefined then { value = mergedValue; } else { };13 | ^14 1311| };1516 … while evaluating definitions from `/nix/store/xfg4bws749i95jvnxhymxmfwailzk38q-source/modules/transposition.nix':1718 … while evaluating definitions from `/nix/store/ci7lj1kzv1qppll6m1f501p2dyl7l3vs-source/flake-module.nix':1920 … while evaluating definitions from `/nix/store/ci7lj1kzv1qppll6m1f501p2dyl7l3vs-source/module-options.nix':2122 … while evaluating the module argument `pkgs' in "/nix/store/ci7lj1kzv1qppll6m1f501p2dyl7l3vs-source/module-options.nix":2324 … noting that argument `pkgs` is not externally provided, so querying `_module.args` instead, requiring `config`2526 … while evaluating definitions from `/nix/store/ci7lj1kzv1qppll6m1f501p2dyl7l3vs-source/flake-module.nix':2728 … while evaluating the option `perSystem.x86_64-darwin.treefmt.pkgs':2930 … while evaluating the module argument `pkgs' in ":anon-10:anon-1":3132 … noting that argument `pkgs` is not externally provided, so querying `_module.args` instead, requiring `config`3334 … while evaluating definitions from `/nix/store/xfg4bws749i95jvnxhymxmfwailzk38q-source/modules/transposition.nix':3536 … while evaluating definitions from `/nix/store/r8f3rr9ljb2jiylblfrig2g76hvh3y1w-source/flake.nix, via option perSystem':3738 … while evaluating the module argument `pkgs' in ":anon-12:anon-1":3940 … noting that argument `pkgs` is not externally provided, so querying `_module.args` instead, requiring `config`4142 … while evaluating definitions from `/nix/store/xfg4bws749i95jvnxhymxmfwailzk38q-source/modules/transposition.nix':4344 (stack trace truncated; use '--show-trace' to show the full, detailed trace)4546 error: Nixpkgs 26.11 has dropped support for x86_64-darwin.4748 The 26.05 stable branch still supports x86_64-darwin, and will49 receive security fixes until the end of 2026. If you use channels,50 you can switch to 26.05 as follows:5152 $ sudo nix-channel --add https://nixos.org/channels/nixpkgs-26.05-darwin nixpkgs53 $ sudo nix-channel --update5455 If this doesn’t work, you may need to run:5657 # Lack of sudo is deliberate:58 $ nix-channel --remove nixpkgs5960 If you use flakes, switch your flake input:6162 inputs.nixpkgs = {63 url = "github:NixOS/nixpkgs/nixpkgs-26.05-darwin";64 };6566 See the release notes for more information and alternatives:6768 https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.11