Application Icons Missing in Ubuntu System Tray

If application icons (e.g., Ulauncher, Caffeine, Guake Terminal, and etc.) are not visible in the top-right system tray, it is often due to a disabled extension or a system change. Below are some common causes and solutions:

1. AppIndicator Extension Disabled

• Ubuntu uses the AppIndicator or KStatusNotifierItem extension to display application icons in the system tray. This extension might be disabled.

• Solution: Verify if the extension is enabled:

  1. Install Gnome Tweaks via Terminal:

     sudo apt install gnome-tweaks
     

  2. Open Gnome Tweaks and ensure the AppIndicator extension is active under the “Extensions” section.

2. Gnome-Shell Extension Issue

• Applications like Ulauncher and Caffeine rely on Gnome Shell Extensions to display their system tray icons. If Gnome has been updated, the extensions may have become incompatible.

• Solution: Reinstall and enable the necessary Gnome Shell extension:

  sudo apt install gnome-shell-extension-appindicator
  gnome-extensions enable appindicatorsupport@rgcjonas.gmail.com
  

NOTE: If the gnome-extensions enable ... command does not work for your system, you can press ALT + F2 and type r to restart the Gnome Shell.