When upgrading from a previous release, please be aware of the following incompatible changes: wmiiSnap has been replaced with wmii_hg, but services.xserver.windowManager.wmii.enable has been updated respectively so this only affects you if you have explicitly installed wmiiSnap. wmiimenu is removed, as it has been removed by the developers upstream. Use wimenu from the wmii-hg package. Gitit is no longer automatically added to the module list in NixOS and as such there will not be any manual entries for it. You will need to add an import statement to your NixOS configuration in order to use it, e.g. ]; } ]]> will include the Gitit service configuration options.