Created attachment 8006 
No checkbox next to the text "handle display brightness keys"

I'm currently having some problems whereby the use of xf86monbrightnessup and xf86monbrightnessdown have stopped working even though they have been assigned to xbacklight-command in the Application shortcuts in the XFCE keyboard settings, I went to have a look at the power manager. There is supposed to be a checkbox next to the text "Handle display brightness keys" but it is missing. I'm attaching a screenshot of the window.

$ xfce4-power-manager --no-daemon --debug

** (xfce4-power-manager:10157): WARNING **: 20:07:50.772: Failed to get name owner: GDBus.Error:org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'org.freedesktop.PowerManagement': no such name


** (xfce4-power-manager:10157): WARNING **: 20:07:50.772: Failed to get name owner: GDBus.Error:org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'org.xfce.PowerManager': no such name

TRACE[xfpm-main.c:205] xfpm_start(): Starting the power manager
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for general-notification
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for lock-screen-suspend-hibernate
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for critical-power-level
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for show-brightness-popup
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for handle-brightness-keys
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for show-tray-icon
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for critical-power-action
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for hibernate-button-action
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for sleep-button-action
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for brightness-level-on-ac
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for brightness-level-on-battery
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for brightness-slider-min-level
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for dpms-sleep-mode
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for inactivity-on-ac
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for inactivity-on-battery
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for inactivity-sleep-mode-on-ac
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for inactivity-sleep-mode-on-battery
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for brightness-on-ac
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for network-manager-sleep
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for logind-handle-power-key
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for logind-handle-suspend-key
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for logind-handle-hibernate-key
TRACE[xfpm-xfconf.c:165] xfpm_xfconf_load(): Using default configuration for heartbeat-command

(xfce4-power-manager:10157): GLib-GObject-WARNING **: 20:07:50.786: ../../../../gobject/gsignal.c:2523: signal 'Changed' is invalid for instance '0x563c622391a0' of type 'GDBusProxy'
TRACE[xfpm-polkit.c:287] xfpm_polkit_init_data(): Using unix session polkit subject
TRACE[xfpm-polkit.c:345] xfpm_polkit_check_auth_intern(): polkit request: (('unix-process', {'pid': <uint32 10157>, 'start-time': <uint64 163371>}), 'org.freedesktop.login1.power-off', @a{ss} {}, uint32 0, '')
TRACE[xfpm-polkit.c:366] xfpm_polkit_check_auth_intern(): Action=org.freedesktop.login1.power-off is authorized=TRUE
TRACE[xfpm-polkit.c:345] xfpm_polkit_check_auth_intern(): polkit request: (('unix-process', {'pid': <uint32 10157>, 'start-time': <uint64 163371>}), 'org.freedesktop.login1.reboot', @a{ss} {}, uint32 0, '')
TRACE[xfpm-polkit.c:366] xfpm_polkit_check_auth_intern(): Action=org.freedesktop.login1.reboot is authorized=TRUE
TRACE[xfpm-polkit.c:345] xfpm_polkit_check_auth_intern(): polkit request: (('unix-process', {'pid': <uint32 10157>, 'start-time': <uint64 163371>}), 'org.freedesktop.login1.suspend', @a{ss} {}, uint32 0, '')
TRACE[xfpm-polkit.c:366] xfpm_polkit_check_auth_intern(): Action=org.freedesktop.login1.suspend is authorized=TRUE
TRACE[xfpm-polkit.c:345] xfpm_polkit_check_auth_intern(): polkit request: (('unix-process', {'pid': <uint32 10157>, 'start-time': <uint64 163371>}), 'org.freedesktop.login1.hibernate', @a{ss} {}, uint32 0, '')
TRACE[xfpm-polkit.c:366] xfpm_polkit_check_auth_intern(): Action=org.freedesktop.login1.hibernate is authorized=TRUE
TRACE[xfpm-power.c:936] xfpm_power_get_power_devices(): Power device detected at : /org/freedesktop/UPower/devices/line_power_AC
TRACE[xfpm-power.c:898] xfpm_power_add_device(): 'line-power' device added
TRACE[xfpm-power.c:936] xfpm_power_get_power_devices(): Power device detected at : /org/freedesktop/UPower/devices/battery_BAT0
TRACE[xfpm-power.c:898] xfpm_power_add_device(): 'battery' device added
TRACE[xfpm-power.c:908] xfpm_power_add_device(): Battery device type 'battery' detected at: /org/freedesktop/UPower/devices/battery_BAT0
TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 124 : ((XfpmButtonKey) BUTTON_POWER_OFF)

(xfce4-power-manager:10157): xfce4-power-manager-WARNING **: 20:07:50.815: could not map keysym 1008ffa8 to keycode

TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 213 : ((XfpmButtonKey) BUTTON_HIBERNATE)
TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 150 : ((XfpmButtonKey) BUTTON_SLEEP)
TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 233 : ((XfpmButtonKey) BUTTON_MON_BRIGHTNESS_UP)
TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 232 : ((XfpmButtonKey) BUTTON_MON_BRIGHTNESS_DOWN)
TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 244 : ((XfpmButtonKey) BUTTON_BATTERY)
TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 238 : ((XfpmButtonKey) BUTTON_KBD_BRIGHTNESS_UP)
TRACE[xfpm-button.c:183] xfpm_button_xevent_key(): Grabbed key 237 : ((XfpmButtonKey) BUTTON_KBD_BRIGHTNESS_DOWN)
TRACE[xfpm-power.c:213] xfpm_power_check_polkit_auth(): using logind suspend backend
TRACE[xfpm-polkit.c:345] xfpm_polkit_check_auth_intern(): polkit request: (('unix-process', {'pid': <uint32 10157>, 'start-time': <uint64 163371>}), 'org.freedesktop.login1.suspend', @a{ss} {}, uint32 0, '')
TRACE[xfpm-polkit.c:366] xfpm_polkit_check_auth_intern(): Action=org.freedesktop.login1.suspend is authorized=TRUE
TRACE[xfpm-polkit.c:345] xfpm_polkit_check_auth_intern(): polkit request: (('unix-process', {'pid': <uint32 10157>, 'start-time': <uint64 163371>}), 'org.freedesktop.login1.hibernate', @a{ss} {}, uint32 0, '')
TRACE[xfpm-polkit.c:366] xfpm_polkit_check_auth_intern(): Action=org.freedesktop.login1.hibernate is authorized=TRUE
TRACE[xfpm-power.c:1446] xfpm_update_blank_time(): Timeout: 10
TRACE[xfpm-power.c:1446] xfpm_update_blank_time(): Timeout: 10
TRACE[xfpm-power.c:1446] xfpm_update_blank_time(): Timeout: 10
TRACE[xfpm-power.c:1446] xfpm_update_blank_time(): Timeout: 0
TRACE[xfpm-manager.c:645] xfpm_manager_inhibit_sleep_systemd(): Inhibiting systemd sleep: handle-power-key:handle-suspend-key:handle-hibernate-key:handle-lid-switch

(xfce4-power-manager:10157): GLib-CRITICAL **: 20:07:50.821: g_error_free: assertion 'error != NULL' failed

(xfce4-power-manager:10157): xfce4-power-manager-WARNING **: 20:07:50.824: Failed to get keyboard max brightness level : GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface “org.freedesktop.UPower.KbdBacklight” on object at path /org/freedesktop/UPower/KbdBacklight

Here are the list of version numbers of Debian packages on which it depends directly:

ii  libc6                     2.27-6
ii  libcairo2                 1.15.12-1
ii  libgdk-pixbuf2.0-0        2.38.0+dfsg-6
ii  libglib2.0-0              2.58.1-2
ii  libgtk-3-0                3.24.0-3
ii  libnotify4                0.7.7-3
ii  libpango-1.0-0            1.42.4-3
ii  libpangocairo-1.0-0       1.42.4-3
ii  libupower-glib3           0.99.8-2
ii  libx11-6                  2:1.6.6-1
ii  libxext6                  2:1.3.3-1+b2
ii  libxfce4ui-2-0            4.12.1-3
ii  libxfce4util7             4.12.1-3
ii  libxfconf-0-2             4.12.1-1
ii  libxrandr2                2:1.5.1-1
ii  upower                    0.99.8-2
ii  xfce4-power-manager-data  1.6.1-1