maintained version, since the previous version was archived. This requires
  some changes to the module configuration, most notable `controlInterface`
  needs migration towards `unbound.host` and requires either the `tcp://` or
  `unix://` URI scheme.

- `odoo` defaults to v16 now, updated from v15.

- `varnish` was upgraded from v7.2.x to v7.4.x. Refer to upgrade guides vor
  [v7.3](https://varnish-cache.org/docs/7.3/whats-new/upgrading-7.3.html) and
  [v7.4](https://varnish-cache.org/docs/7.4/whats-new/upgrading-7.4.html). The
  current LTS version is still offered as `varnish60`.

- `util-linux` is now supported on Darwin and is no longer an alias to
  `unixtools`. Use the `unixtools.util-linux` package for access to the Apple
  variants of the utilities.

- `services.keyd` changed API. Now you can create multiple configuration files.

- `baloo`, the file indexer and search engine used by KDE now has a patch to
  prevent files from constantly being reindexed when the device IDs of the
  their underlying storage change. This happens frequently when using btrfs or
  LVM. The patch has not yet been accepted upstream but it provides a
  significantly improved experience. When upgrading, reset baloo to get a clean
  index: `balooctl disable ; balooctl purge ; balooctl enable`.

- The `vlock` program from the `kbd` package has been moved into its own
  package output and should now be referenced explicitly as `kbd.vlock` or
  replaced with an alternative such as the standalone `vlock` package or
  `physlock`.

- `fileSystems.<name>.autoFormat` now uses `systemd-makefs`, which does not
  accept formatting options. Therefore, `fileSystems.<name>.formatOptions` has
  been removed.

- `fileSystems.<name>.autoResize` uses `systemd-growfs` to resize the file
  system online in Stage 2 now. This means that `f2fs` and `ext2` can no longer
  be auto resized, while `xfs` and `btrfs` now can be.

- `fuse3` has been updated from v3.11.0 to v3.16.2. Refer to the
  [changelog](https://github.com/libfuse/libfuse/blob/fuse-3.16.2/ChangeLog.rst#libfuse-3162-2023-10-10)
  for an overview of the changes.

  Unsupported mount options are no longer silently accepted [(since
  3.15.0)](https://github.com/libfuse/libfuse/blob/fuse-3.16.2/ChangeLog.rst#libfuse-3150-2023-06-09).
  The [affected mount
  options](https://github.com/libfuse/libfuse/commit/dba6b3983af34f30de01cf532dff0b66f0ed6045)
  are: `atime`, `diratime`, `lazytime`, `nolazytime`, `relatime`, `norelatime`,
  `strictatime`.

  For example,

  ```bash
  $ sshfs 127.0.0.1:/home/test/testdir /home/test/sshfs_mnt -o atime
  ```

  would previously terminate successfully with the mount point established, now
  it outputs the error message ``fuse: unknown option(s): `-o atime'`` and
  terminates with exit status 1.

- `nixos-rebuild {switch,boot,test,dry-activate}` runs the system
  activation inside `systemd-run` now, creating an ephemeral systemd service
  and protecting the system switch against issues like network disconnections
  during remote (e.g. SSH) sessions. This has the side effect of running the
  switch in an isolated environment, that could possible break post-switch
  scripts that depends on things like environment variables being set. If you
  want to opt-out from this behavior for now, you may set the
  `NIXOS_SWITCH_USE_DIRTY_ENV` environment variable before running
  `nixos-rebuild`. However, keep in mind that this option will be removed in
  the future.

- The `services.vaultwarden.config` option default value was changed to make
  Vaultwarden only listen on localhost, following the [secure defaults for most
  NixOS services](https://github.com/NixOS/nixpkgs/issues/100192).

- `services.lemmy.settings.federation` was removed in v0.17.0 and no longer has
  any effect. To enable federation, the hostname must be set in the
  configuration file and then federation must be enabled in the admin web UI.
  Refer to the [release
  notes](https://github.com/LemmyNet/lemmy/blob/c32585b03429f0f76d1e4ff738786321a0a9df98/RELEASES.md#upgrade-instructions)