# [archived] macOS Sequoia breaks existing Lix installations

macOS 15 "Sequoia" changed the user ID ranges used by the system, such that some of the IDs for existing Nix build users got used by some new system features instead.

The symptom of this problem is that Nix builds will fail out with the following error, since the previous user ID used by `_nixbld1` got clobbered by Apple's updater:

```
error: the user '_nixbld1' in the group 'nixbld' does not exist
```

To fix this on your system, run the latest Lix installer (any version of the Lix installer ≥ `2.91.0-1`) with the `repair sequoia` option:

```
curl -sSf -L https://install.lix.systems/lix | sh -s -- repair sequoia
```

You may run this before or after updating to Sequoia (to run it *before* the upgrade, add `--move-existing-users` to the end of the command); it just migrates the user IDs used by Lix to a range recommended by Apple.

Relevant links:
- <https://git.lix.systems/lix-project/lix-installer/issues/24>
- <https://github.com/NixOS/nix/pull/11075>
- <https://github.com/DeterminateSystems/nix-installer/issues/1115>