Posting as it took me some time to find a solution for Ubuntu 20.04, even though this is an old question, it might help others looking for this.
This is where I found the method: https://help.gnome.org/admin/system-admin-guide/stable/dconf-custom-defaults.html.en
What I tried and didn't work:
I tried to edit the schemas folder directly (for people new to Ubuntu like me, the folder I'm referring to is found at /usr/share/glib-2.0/schemas/
). The configuration file that I needed to edit was org.gnome.desktop.background.gschema.xml
, yet for some reason, that wouldn't be applied to the new user, plus it is likely bad practice to edit these configuration files directly.
I then followed gnome.org 's guide and created a file here:
sudo nano /etc/dconf/db/local.d/01-background
Then add the following:
# dconf path
[org/gnome/desktop/background]
dconf key names and their corresponding values
picture-uri='file:///usr/share/backgrounds/your-own-wallpaper-here.jpg'
Make sure that your wallpaper is located at /usr/share/backgrounds/
and that you've edited either focal-wallpapers.xml
or ubuntu-wallpapers.xml
found at /usr/share/gnome-background-properties/
to include your wallpaper image (there are other posts that explain how to do this).
Lastly update dconf by running:
sudo dconf update
I would recommend rebooting, then creating a new user to test whether it's working. I hope this helps, it worked for me, let me know if you have better solutions or slightly improvements to this method.