I broke the Gnome Settings --> Background

I was working toward creating a new background image slideshow. I created a new XML pair for the settings and for the slideshow. My proof-of-concept files worked (two images and transitions moving back and forth once the new slideshow was selected from Settings).

This PoC used symlinks in a single folder. My next step was t o test two images from directly within the folder hierarchy. These file paths may contain special characters. I selected two files where one merely included spaces and a second which included three special characters (the ’ and the open and closed squares: []).

The file with the spaces worked as expected; the other did not display in the slideshow. I then added quotations around the paths to see if this would remedy the matter. It did not.

However, this testing broke the background settings. I suspect whatever ingests those XML files now contains corrupted data and can no longer do its job. That’s just a guess.

What do I mean by broken? There are no longer any images or slideshow objects listed in the settings one might select. The newly created was present until I removed those files. The default (two slideshows and a handful of images) are all gone from the settings dialog (though all remain in the file system as expected).

Once I removed my new slideshow (both XML files) and chose a different file as a background (using the still functional Add Picture button), that new slideshow also vanished from the background settings.

Reboots have not helped and this (of course) impacts all users.

How can I fix this? What did that ingested XML break?

Ubuntu 22.04