I had a weird issue where GNOME wouldn't start on my laptop after starting it up fresh. GDM kept attempting to start and failing – the screen kept flickering but staying black.

I didn't find anything useful in the logs, so I tried starting cinnamon via "xinit" (using .xinitrc which was set up for cinnamon), and it spat out this message:

GLib-GIO-ERROR**: No GSettings schemas are installed on the system 

I then ran, as root:

# glib-compile-schemas /usr/share/glib-2.0/schemas/

This resolved the problem. But it's a problem that it broke in the first place, and that this is a source of fragility that can render any gtk+ application broken.

Ideally, the system would be more robust, or identify this problem and automatically fix it, or inform the user of the problem and assist with fixing it.