Why is locate suddenly giving me permission denied?

Help
1

I’ve used locate for years, but today it gave me:

$ locate hukarz
locate: can not open `/var/cache/locatedb': Permission denied

Something changed recently. I need to be a member of a special group?

  services.locate = {
    enable = true;
    locate = pkgs.mlocate;
    interval = "hourly";
  };

  services.locate.localuser = null;

  users.users.b0ef.extraGroups = [ "mlocate" ];
2

Still the same after a restart. I’m stumped as to what has happened here.