error: Nixpkgs 26.11 has dropped support for x86_64-darwin.

The 26.05 stable branch still supports x86_64-darwin, and will
receive security fixes until the end of 2026. If you use channels,
you can switch to 26.05 as follows:

    $ sudo nix-channel --add https://nixos.org/channels/nixpkgs-26.05-darwin nixpkgs
    $ sudo nix-channel --update

If this doesn’t work, you may need to run:

    # Lack of sudo is deliberate:
    $ nix-channel --remove nixpkgs

If you use flakes, switch your flake input:

    inputs.nixpkgs = {
      url = "github:NixOS/nixpkgs/nixpkgs-26.05-darwin";
    };

See the release notes for more information and alternatives:

  https://nixos.org/manual/nixpkgs/unstable/release-notes#x86_64-darwin-26.11

       at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/trivial.nix:1003:37
       … while calling the 'throw' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/trivial.nix:1003:37
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/trivial.nix:1003:19
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/pkgs/top-level/default.nix:113:9
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/trivial.nix:982:40
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/pkgs/top-level/default.nix:108:6
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/pkgs/top-level/default.nix:21:1
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/pkgs/top-level/impure.nix:55:1
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/pkgs/top-level/impure.nix:12:1
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/flake.nix:234:12
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/flake.nix:233:11
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1343:17
       … while evaluating the attribute 'legacyPackages.x86_64-darwin' at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1343:9
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:155:13
       … while evaluating the attribute 'nixpkgs'
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:155:13
       … while evaluating the attribute 'self.godoc' at «call-flake»:71:44
       … while calling anonymous lambda at /nix/store/8j91fdd82rvsx7bllwxf349fx6kbxck3-source/nix/package.nix:1:1
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/customisation.nix:161:20
       … while calling the '__isAttrs' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/customisation.nix:175:12
       … while calling 'f'' at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/customisation.nix:159:9
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/customisation.nix:323:7
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/customisation.nix:308:19
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:590:37
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:590:22
       … while evaluating the attribute 'default' at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:548:11
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:163:10
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:60
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:53
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:45
       … while calling the '__filter' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:45
       … while calling the 'removeAttrs' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:28
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:23
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:162:5
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:161:13
       … while evaluating the attribute 'self.packages.x86_64-darwin' at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1343:9
       … while calling the 'removeAttrs' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:28
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:667:23
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:162:5
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:161:13
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:743:18
       … while calling the '__mapAttrs' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1079:42
       … while calling the '__attrValues' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1079:30
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1079:23
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:377:33
       … while calling the '__length' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/lists.nix:1142:19
       … while calling the '__genList' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/lists.nix:1144:5
       … while calling 'reverseList' at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/lists.nix:1139:5
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:377:20
       … while calling the '__concatLists' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:377:7
       … while calling the '__listToAttrs' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:376:5
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:375:8
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:733:15
       … while calling the '__mapAttrs' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1079:42
       … while calling the '__attrValues' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1079:30
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1079:23
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1045:36
       … while calling the '__listToAttrs' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1045:23
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1045:18
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:732:14
       … while calling the '__elemAt' builtin at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1615:11
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1610:16
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1620:11
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1610:16
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1620:11
       … while calling anonymous lambda at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1610:16
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1626:7
       … while calling 'mergeAttrsList' at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1605:5
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:729:9
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:728:9
       … from call site at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:63:53
       … while calling anonymous lambda at /nix/store/0j8v7y6i81c0g1gjqp37qy05225k4ags-source/lib/default.nix:63:45
       … from call site at /nix/store/fd5qgysvbfx27wj651swlr899w6jnbwd-source/lib/attrsets.nix:1343:17
       … while calling the '__isAttrs' builtin at «string»:25:9
       … while calling 'prune' at «string»:24:5