I'm trying to apply icon themes in my Ubuntu 18.04 setup, and for some reason, certain icons won't have icons applied to them, even though I know they're icons designed for said applications. When I was on Ubuntu 16.04, I used the numix circle icon theme, and there was a circle icon for Discord and Gimp. Now, with the same icon theme, those icons won't be applied. I tried the papirus icon theme as well, with the same result. How can I fix this? I applied the icon theme using the gnome-tweak tool.


If you installed the applications via snap, there is a problem with snaps accessing some global settings like themes. See https://forum.snapcraft.io/t/use-the-system-gtk-theme/496/3 for a more technical description.


You can change the app icon yourself though, and pick the Numix one. You have to start Files/Nautilus as Super User with

sudo nautilus

find the app, right click, properties, then click on the app icon, look for the Numix one and apply.


Try the following commands in ubuntu terminal:

sudo apt update --fix-missing && sudo apt upgrade

The above command for update and fix the incomplete updates and upgrades

sudo apt-get install --reinstall ubuntu-desktop

The above command reinstall ubuntu desktop icons and theme

sudo apt-get install --reinstall gnome-shell-extensions

sudo apt-get install --reinstall whatevertheme

The above two commands are for reinstalling gnome shell extensions and troubled themes.

This may fix all the issues of missing icons or themes.

If the problem still persists please write here will give few more instructions...


Iam using ubuntu 20.04lts

Icon themes are generally under /usr/share/icons/${THEME_NAME}. For the purposes of examples in this guide, I'll be using the Numix-Circle icons. Now open terminal and type sudo nautilus this will open file manager with super user now follow these steps.

Snaps are installed under /var/lib/snapd. Their corresponding desktop files are under /var/lib/snapd/desktop/applications. Opening any desktop file with text editor we can see a line that begins with Icon=.

Go into your theme directory that you found earlier, and find the corresponding icon in there. For Numix, these are under /usr/share/icons/Numix-Circle/48/apps. Replace the path in the .desktop file with your desire icon. Restart your computer.

Now no longer you will see ugly square icons in your dock.

Note: If you update your snap application you have to repeat this process again.

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