Comment 3 for bug 1822937

What one would see from terminal (pkexec ls works fine)

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 175, in activate_name_owner
    return self.get_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 361, in get_name_owner
    's', (bus_name,), **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'com.ubuntu.ScreenResolution.Mechanism': no such name

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/share/screen-resolution-extra/nvidia-polkit.py", line 75, in <module>
    operation_status = main(options)
  File "/usr/share/screen-resolution-extra/nvidia-polkit.py", line 42, in main
    conf = get_xkit_service()
  File "/usr/share/screen-resolution-extra/nvidia-polkit.py", line 33, in get_xkit_service
    service_object = dbus.SystemBus().get_object(SERVICE_NAME, OBJECT_PATH)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: Cannot launch daemon, file not found or permissions invalid

ERROR: Unable to open X config file '/etc/X11/xorg.conf' for writing.