Comment 11 for bug 1795703

Same problem here (I think).

Stock Ubuntu 18.04.1 LTS
gnome-shell-extension-ubuntu-dock version 0.9.1ubuntu18.04.1

The dock has disappeared overnight (pretty sure that it's not related to any updates, since auto-updates are off and /var/log/apt/history.log does not show any installs/upgrades more recent than January 14.) I still have a gray bar with the time on top and the word "Activities" in the top left corner. It shows up if I click on "Activities" or press the Windows key on the keyboard, then disappears again.

Options in the "Dock" tab in Ubuntu settings (Auto-hide, Position on screen) have no effect.

Unlike the original reporter, my system was rebooted about 24 hours ago.

Reviewing the event journal, I see the following appear last evening:

Jan 28 21:21:56 aidev-System-Product-Name gnome-shell[3405]: JS WARNING: [/<email address hidden>/docking.js 1778]: reference to undefined property "_workspaceIsolation"
(...)
Jan 28 21:22:25 aidev-System-Product-Name gnome-shell[3405]: g_array_unref: assertion 'array' failed
Jan 28 21:22:25 aidev-System-Product-Name upowerd[2154]: unhandled action 'unbind' on /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1.3/3-1.3:1.2/0003:046D:C52B.0139/0003:046D:200A.013B
Jan 28 21:22:25 aidev-System-Product-Name upowerd[2154]: unhandled action 'unbind' on /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1.3/3-1.3:1.2/0003:046D:C52B.0139
Jan 28 21:22:25 aidev-System-Product-Name upowerd[2154]: unhandled action 'unbind' on /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1.3/3-1.3:1.2
Jan 28 21:22:25 aidev-System-Product-Name upowerd[2154]: unhandled action 'unbind' on /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1.3
Jan 28 21:22:29 aidev-System-Product-Name /usr/lib/gdm3/gdm-x-session[3271]: (--) NVIDIA(GPU-0): DFP-0: disconnected
(...)
Jan 28 21:22:29 aidev-System-Product-Name /usr/lib/gdm3/gdm-x-session[3271]: (--) NVIDIA(GPU-0): DFP-6: disconnected
Jan 28 21:22:29 aidev-System-Product-Name /usr/lib/gdm3/gdm-x-session[3271]: (--) NVIDIA(GPU-0): DFP-6: Internal TMDS
Jan 28 21:22:29 aidev-System-Product-Name /usr/lib/gdm3/gdm-x-session[3271]: (--) NVIDIA(GPU-0): DFP-6: 165.0 MHz maximum pixel clock
Jan 28 21:22:29 aidev-System-Product-Name /usr/lib/gdm3/gdm-x-session[3271]: (--) NVIDIA(GPU-0):
Jan 28 21:22:29 aidev-System-Product-Name gnome-shell[3405]: JS ERROR: TypeError: this._workspaceIsolation is undefined
                                                             DockManager<._deleteDocks@/<email address hidden>/docking.js:1778:9
                                                             wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22
                                                             DockManager<._toggle@/<email address hidden>/docking.js:1662:9
                                                             wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22

(I think the dock was still up after 21:22, but I'm not positive.)

There are lots of other recurrent Gnome-related errors in the log, which may or may not be related. These include:

Jan 29 12:30:20 aidev-System-Product-Name gnome-shell[3405]: Object St.Icon (0x55980a2b1f10), has been already finalized. Impossible to set any property to it.
Jan 29 12:30:20 aidev-System-Product-Name org.gnome.Shell.desktop[3405]: == Stack trace for context 0x559809c11340 ==
Jan 29 12:30:20 aidev-System-Product-Name org.gnome.Shell.desktop[3405]: #0 0x55980a0b7498 i resource:///org/gnome/shell/ui/osdWindow.js:206 (0x7f2bd42c7780 @ 231)
(...)
Jan 29 12:30:20 aidev-System-Product-Name gnome-shell[3405]: Object St.BoxLayout (0x55980a2b0e50), has been already finalized. Impossible to set any property to it.
(...)
(repeated ~20 times for different options)

Jan 29 12:31:28 aidev-System-Product-Name gnome-shell[3405]: g_array_unref: assertion 'array' failed