XUbuntu 22.04.5 LTS | xfce4 | computer won't wake up after screen locks, and now GUI stopped working

One more piece of information: if I press ctrl-alt-f1 and login to the CLI, then there is an error message

xset: unable to open display ""

but I still get a prompt and can issue commands, as long as I don't hit ctrl-alt-f7 to activate the GUI:
once I login to the GUI, I can't get back to the command line.
How do I repair the xfce4 GUI?

Here's a possible solution to your XUbuntu screen locking and GUI issues:

1. To restore your GUI, try this from the command line (Ctrl+Alt+F1):
   ```
   mv ~/.config ~/.config_old
   sudo reboot
   ```
   This should reset XFCE to default settings.

2. If GUI works, edit LightDM config:
   ```
   sudo nano /etc/lightdm/lightdm.conf
   ```
   Add under [Seat:*]:
   ```
   logind-check-graphical=true
   xserver-command=X -s 0 dpms
   ```

3. Update your system:
   ```
   sudo apt update && sudo apt upgrade
   ```

4. Check graphics drivers:
   ```
   lspci | grep VGA
   ```
   Ensure correct drivers are installed.

5. Investigate power management:
   ```
   sudo apt install powertop && sudo powertop
   ```
   Look for unusual power behaviors.

6. Check logs:
   ```
   journalctl -b -p err
   ```
   Look for display/power/XFCE errors.

If issues persist:
- Try a different desktop environment
- Create a new user account to test
- Check hardware, especially on older systems

Backup data before major changes. Let us know if you need more details on any step!

Thanks for your help! You wrote:

"If GUI works, edit LightDM config:
sudo nano /etc/lightdm/lightdm.conf
Add under [Seat:*]:
logind-check-graphical=true
xserver-command=X -s 0 dpms"

If the GUI does not work, should I still do this step (from the ctrl-alt-f1 CLI), or should I skip it?

By the way, when I just did it, then the GUI still failed, then I unplugged and re-plugged the monitor cable and the GUI actually worked for a few seconds.

My theory is that "X" does not know which display to connect to, and something i had previously in .config told it to but it got lost even though I thought i had backed it up. And unfortunately commands involving "xset" or "xrandr" return errors when I try to set the display to ":0" (export DISPLAY=0 or export DISPLAY=:0) which should be the default, anyway.

I can try replacing the adapter and cable and see what happens, but in the meantime, please let me know if I should edit /etc/lightdm/lightdm.conf if the gui does NOT work? Thank you.

Thank you again for your help. Regarding troubleshooting step #2:

"2. If GUI works, edit LightDM config:

   sudo nano /etc/lightdm/lightdm.conf

   Add under [Seat:*]:

   logind-check-graphical=true
   xserver-command=X -s 0 dpms"

should I also do this if the GUI does *not* work, or should I skip it, or save it till the end? I find the "X Window" system terminology confusing, as it seems the "server" and the "client" are reversed, with the "server" making requests to the "client"; what do these commands actually do?

Regarding step 4, the output of "lspci | grep VGA" is:
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Wani [Radeon R5/R6/R7 Graphics] (rev 87)

Regarding step 5, I tried installing powertop, but none of the keyboard commands work! (Only thing that works is Ctrl-C.) And if I redirect the output to a file then it is not easily readable.

Regarding step 6, I can private-message you the logs; however, I think the ".xsession-errors" file might be more interesting:

dbus-update-activation-environment: setting DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
dbus-update-activation-environment: setting DISPLAY=:0
dbus-update-activation-environment: setting XAUTHORITY=/home/jdl/.Xauthority
/etc/X11/Xsession.d/30x11-common_xresources: line 16: has_option: command not found
/etc/X11/Xsession.d/75dbus_dbus-launch: line 9: has_option: command not found
dbus-update-activation-environment: setting QT_ACCESSIBILITY=1
/etc/X11/Xsession.d/90x11-common_ssh-agent: line 9: has_option: command not found
dbus-update-activation-environment: setting SHELL=/bin/bash
dbus-update-activation-environment: setting QT_ACCESSIBILITY=1
dbus-update-activation-environment: setting XDG_CONFIG_DIRS=/etc/xdg/xdg-xubuntu:/etc/xdg
dbus-update-activation-environment: setting XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session0
dbus-update-activation-environment: setting CLUTTER_BACKEND=x11
dbus-update-activation-environment: setting LANGUAGE=en_US
dbus-update-activation-environment: setting DESKTOP_SESSION=xubuntu
dbus-update-activation-environment: setting PWD=/home/jdl
dbus-update-activation-environment: setting XDG_SESSION_DESKTOP=xubuntu
dbus-update-activation-environment: setting LOGNAME=jdl
dbus-update-activation-environment: setting QT_QPA_PLATFORMTHEME=gtk2
dbus-update-activation-environment: setting XDG_SESSION_TYPE=x11
dbus-update-activation-environment: setting GPG_AGENT_INFO=/run/user/1000/gnupg/S.gpg-agent:0:1
dbus-update-activation-environment: setting XAUTHORITY=/home/jdl/.Xauthority
dbus-update-activation-environment: setting XDG_GREETER_DATA_DIR=/var/lib/lightdm-data/jdl
dbus-update-activation-environment: setting GDM_LANG=en_US
dbus-update-activation-environment: setting HOME=/home/jdl
dbus-update-activation-environment: setting IM_CONFIG_PHASE=1
dbus-update-activation-environment: setting LANG=en_US.UTF-8
dbus-update-activation-environment: setting XDG_CURRENT_DESKTOP=XFCE
dbus-update-activation-environment: setting XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
dbus-update-activation-environment: setting XDG_SESSION_CLASS=user
dbus-update-activation-environment: setting GTK_OVERLAY_SCROLLING=0
dbus-update-activation-environment: setting USER=jdl
dbus-update-activation-environment: setting DISPLAY=:0
dbus-update-activation-environment: setting SHLVL=1
dbus-update-activation-environment: setting XDG_RUNTIME_DIR=/run/user/1000
dbus-update-activation-environment: setting XDG_DATA_DIRS=/usr/share/xubuntu:/usr/share/xfce4:/usr/local/share:/usr/share:/var/lib/snapd/desktop
dbus-update-activation-environment: setting PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
dbus-update-activation-environment: setting GDMSESSION=xubuntu
dbus-update-activation-environment: setting DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
dbus-update-activation-environment: setting _=/usr/bin/dbus-update-activation-environment
/usr/bin/iceauth: creating new authority file /run/user/1000/ICEauthority

(wrapper-2.0:2741): GLib-GIO-CRITICAL **: 08:44:11.051: g_file_new_for_path: assertion 'path != NULL' failed

(wrapper-2.0:2741): GLib-GIO-CRITICAL **: 08:44:11.052: g_file_monitor_file: assertion 'G_IS_FILE (file)' failed

(wrapper-2.0:2741): GLib-GObject-WARNING **: 08:44:11.052: invalid (NULL) pointer instance

(wrapper-2.0:2741): GLib-GObject-CRITICAL **: 08:44:11.052: g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed

(wrapper-2.0:2741): Gtk-WARNING **: 08:44:11.052: Attempting to add a widget with type GtkToggleButton to a container of type XfcePanelPlugin, but the widget is already inside a container of type XfcePanelPlugin, please remove the widget from its existing container first.

(process:2771): ayatana-indicator-application-service-WARNING **: 08:44:11.241: Unable to get watcher name 'org.kde.StatusNotifierWatcher'

** (xfce4-power-manager:2773): WARNING **: 08:44:11.286: 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:2773): WARNING **: 08:44:11.289: Failed to get name owner: GDBus.Error:org.freedesktop.DBus.Error.NameHasNoOwner: Could not get owner of name 'org.xfce.PowerManager': no such name

** (wrapper-2.0:2743): WARNING **: 08:44:11.320: No outputs have backlight property

(wrapper-2.0:2741): Gtk-WARNING **: 08:44:11.549: Negative content width -3 (allocation 1, extents 2x2) while allocating gadget (node button, owner GtkToggleButton)

(polkit-gnome-authentication-agent-1:2777): GLib-CRITICAL **: 08:44:11.549: g_variant_new_string: assertion 'string != NULL' failed

(polkit-gnome-authentication-agent-1:2777): polkit-gnome-1-WARNING **: 08:44:11.561: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files

(wrapper-2.0:2739): Gtk-WARNING **: 08:44:11.646: Negative content width -3 (allocation 1, extents 2x2) while allocating gadget (node button, owner GtkToggleButton)

** (xfce4-screensaver:2770): WARNING **: 08:44:11.731: screensaver already running in this session

(wrapper-2.0:2743): Gtk-CRITICAL **: 08:44:12.126: gtk_icon_theme_has_icon: assertion 'icon_name != NULL' failed

(wrapper-2.0:2743): Gtk-CRITICAL **: 08:44:12.126: gtk_icon_theme_has_icon: assertion 'icon_name != NULL' failed

(wrapper-2.0:2743): Gtk-CRITICAL **: 08:44:12.146: gtk_icon_theme_has_icon: assertion 'icon_name != NULL' failed

(wrapper-2.0:2743): Gtk-CRITICAL **: 08:44:12.158: gtk_icon_theme_has_icon: assertion 'icon_name != NULL' failed

(wrapper-2.0:2743): Gtk-WARNING **: 08:44:12.304: Negative content width -3 (allocation 1, extents 2x2) while allocating gadget (node button, owner PowerManagerButton)

(wrapper-2.0:2746): Gtk-WARNING **: 08:44:12.536: Negative content width -3 (allocation 1, extents 2x2) while allocating gadget (node button, owner PulseaudioButton)

(xfce4-power-manager:2773): GLib-GObject-WARNING **: 08:44:12.567: ../../../gobject/gsignal.c:2613: signal 'Changed' is invalid for instance '0x55dc8e997140' of type 'GDBusProxy'

(xfce4-power-manager:2773): xfce4-power-manager-WARNING **: 08:44:12.618: could not map keysym 1008ffa8 to keycode

** (xfce4-power-manager:2773): WARNING **: 08:44:12.631: No outputs have backlight property

(xfce4-power-manager:2773): xfce4-power-manager-WARNING **: 08:44:12.747: It seems the kernel brightness switch handling value was not restored properly on exit last time, xfce4-power-manager will try to restore it this time.
xfce4-power-manager-Message: 08:44:13.257: Set kernel brightness switch to 0

(xfce4-power-manager:2773): xfce4-power-manager-WARNING **: 08:44:13.300: Failed to get keyboard max brightness level : GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: Object does not exist at path “/org/freedesktop/UPower/KbdBacklight”

In conclusion, should I do troubleshooting step #2 (above) if the GUI still does not work? And, by looking at the xsession-errors, can you please advise what the next troubleshooting step should be? Thank you again for your help.

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