How to fix missing Gtk Icons in Snap building

snapcraft
1

I am trying to build my first snap and, while built, fails to launch due to an error about missing icons. Specifically, it dies with this error:

(tqsl:2376313): Gtk-WARNING **: 23:08:09.016: Could not load a pixbuf from /org/gtk/libgtk/icons/48x48/status/image-missing.png.
This may indicate that pixbuf loaders or the mime database could not be found.
**
Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /org/gtk/libgtk/icons/48x48/status/image-missing.png: Unrecognized image file format (gdk-pixbuf-error-quark, 3)
Bail out! Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /org/gtk/libgtk/icons/48x48/status/image-missing.png: Unrecognized image file format (gdk-pixbuf-error-quark, 3)
Aborted (core dumped)

I assume this means it is missing some required package or configuration. I found that I could get image-missing.png from the package gnome-icon-theme which I’ve added to the staging list. The icon is now installed at /usr/share/icons/gnome/48x48/status/image-missing.png, but this still doesn’t match the path it is looking for it in. Both this icon filename and the /opt/gtk/libgtk/icons/ prefix seem to come from the library libgtk-3.so so this seems to be some kind of built-in behavior, however, I am at a loss as to how to fix it.

2

This is not about a missing icon but about the missing pixbuf loader for png support, the icon is just fallout of the former error…

You can either run the command to update the pixbuf loader list from an override-prime step, so the config points to the correct places inside the snap to be able to load the loaders or simply use the gnome extension which will do all this automatically for you…