Identify a GNOME application that acquired an inhibitor lock and blocks power-off or reboot operation.
The issue
Try to power-off or reboot the machine.
$ sudo reboot
Operation inhibited by "milosz" (PID 165825 "gnome-session-b", user milosz), reason is "user session inhibited". Please retry operation after closing inhibitors and logging out other users. Alternatively, ignore inhibitors and users with 'systemctl reboot -i'.
There is an inhibition lock that is blocking the operation. It can be anything as the lock can be acquired by an application to perform an upgrade, ask user a question or simply play multimedia.
Ignore the inhibitors
The easiest solution is to simply ignore inhibitors.
$ sudo systemctl reboot -i
You can stop here. No questions asked.
Identify an application that acquired an inhibitor lock
Use systemd to lists all active inhibition locks.
$ systemd-inhibit --list
WHO UID USER PID COMM WHAT WHY MODE ModemManager 0 root 1322 ModemManager sleep ModemManager needs to reset devices delay NetworkManager 0 root 1207 NetworkManager sleep NetworkManager needs to turn off networks delay UPower 0 root 1941 upowerd sleep Pause device polling delay Unattended Upgrades Shutdown 0 root 1329 unattended-upgr shutdown Stop ongoing upgrades or perform upgrades before shutdown delay GNOME Shell 1000 milosz 165844 gnome-shell sleep GNOME needs to lock the screen delay milosz 1000 milosz 165990 gsd-media-keys handle-power-key:handle-suspend-key:handle-hibernate-key GNOME handling keypresses block milosz 1000 milosz 165825 gnome-session-b shutdown user session inhibited block milosz 1000 milosz 165990 gsd-media-keys sleep GNOME handling keypresses delay milosz 1000 milosz 165991 gsd-power sleep GNOME needs to lock the screen delay 9 inhibitors listed.
In this specific case, it will not provide details required to identify the culprit, so let’s send a message to a D-Bus message bus.
Display a list of all the inhibitors that are currently known to the session manager.
$ dbus-send --print-reply --dest=org.gnome.SessionManager /org/gnome/SessionManager org.gnome.SessionManager.GetInhibitors
method return time=1642024889.110099 sender=:1.41 -> destination=:1.355 serial=354 reply_serial=2
array [
object path "/org/gnome/SessionManager/Inhibitor2"
]
Display an application ID associated with this particular inhibitor.
$ dbus-send --print-reply --dest=org.gnome.SessionManager /org/gnome/SessionManager/Inhibitor2 org.gnome.SessionManager.Inhibitor.GetAppId
method return time=1642024906.006541 sender=:1.41 -> destination=:1.356 serial=355 reply_serial=2 string "org.gnome.gedit"
Display the reason associated with this particular inhibitor.
$ dbus-send --print-reply --dest=org.gnome.SessionManager /org/gnome/SessionManager/Inhibitor2 org.gnome.SessionManager.Inhibitor.GetReason
method return time=1642025519.024147 sender=:1.41 -> destination=:1.375 serial=367 reply_serial=2 string "There are unsaved documents"
The culprit is identified as the text editor for the GNOME Desktop (gedit) acquired an inhibitor lock as there are unsaved documents.
Close X11 application to release an inhibitor lock
Display the X identifier associated with the application that acquired an inhibitor lock.
$ dbus-send --print-reply --dest=org.gnome.SessionManager /org/gnome/SessionManager/Inhibitor2 org.gnome.SessionManager.Inhibitor.GetToplevelXid
method return time=1642025699.728285 sender=:1.41 -> destination=:1.380 serial=372 reply_serial=2 uint32 44040440
Display an active X11 display name.
$ dbus-send --system --print-reply --dest=org.gnome.DisplayManager /org/gnome/DisplayManager/Displays org.freedesktop.DBus.Introspectable.Introspect | grep node\ name
<node name="93867397657696"/>
$ dbus-send --system --print-reply --dest=org.gnome.DisplayManager /org/gnome/DisplayManager/Displays/93867397657696 org.gnome.DisplayManager.Display.GetX11DisplayName
method return time=1642027597.153035 sender=:1.19 -> destination=:1.883 serial=350 reply_serial=2 string ":3"
Kill the application that acquired an inhibitor lock.
$ DISPLAY=:3 xkill -id 44040440
xkill: killing creator of resource 0x2a000f8
Use systemd to lists all active inhibition locks.
$ systemd-inhibit --list
WHO UID USER PID COMM WHAT WHY MODE ModemManager 0 root 1322 ModemManager sleep ModemManager needs to reset devices delay NetworkManager 0 root 1207 NetworkManager sleep NetworkManager needs to turn off networks delay UPower 0 root 1941 upowerd sleep Pause device polling delay Unattended Upgrades Shutdown 0 root 1329 unattended-upgr shutdown Stop ongoing upgrades or perform upgrades before shutdown delay GNOME Shell 1000 milosz 165844 gnome-shell sleep GNOME needs to lock the screen delay milosz 1000 milosz 165990 gsd-media-keys handle-power-key:handle-suspend-key:handle-hibernate-key GNOME handling keypresses block milosz 1000 milosz 165990 gsd-media-keys sleep GNOME handling keypresses delay milosz 1000 milosz 165991 gsd-power sleep GNOME needs to lock the screen delay 8 inhibitors listed.
Display a list of all the inhibitors that are currently known to the session manager.
$ dbus-send --print-reply --dest=org.gnome.SessionManager /org/gnome/SessionManager org.gnome.SessionManager.GetInhibitors
method return time=1642027705.692889 sender=:1.41 -> destination=:1.385 serial=381 reply_serial=2 array [ ]
Perform the power-off or reboot the machine.
$ sudo reboot
Connection to 172.16.0.200 closed by remote host. Connection to 172.16.0.200 closed.
It was a little adventure!
Additional notes
Use gdbus a tool for working with D-Bus objects for initial inspection, as it is easier due to tab completion.
$ gdbus call --system --dest org.gnome.DisplayManager --object-path /org/gnome/DisplayManager/Displays/93867397657696 --method org.gnome.DisplayManager.Display.GetX11DisplayName
(':3',)
