Comment 0 for bug 1574544

I installed Xubuntu 16.04 as a new installation, and light-locker-settings cannot be opened. Starting from command line I get a following backtrace:

/usr/share/light-locker-settings/light-locker-settings/ PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
  from gi.repository import Gtk, GLib, Gio
Traceback (most recent call last):
  File "/usr/share/light-locker-settings/light-locker-settings/", line 697, in <module>
    main = LightLockerSettings()
  File "/usr/share/light-locker-settings/light-locker-settings/", line 98, in __init__
  File "/usr/share/light-locker-settings/light-locker-settings/", line 454, in init_settings
    if self.check_running_process("xfce4-power-manager"):
  File "/usr/share/light-locker-settings/light-locker-settings/", line 219, in check_running_process
    for pid in psutil.get_pid_list():
AttributeError: 'module' object has no attribute 'get_pid_list'

There is a similar backtrace in #1323807, but the original case seems different.