as discussed on irc, it's because of the default background value:
$ gsettings get org.gnome.desktop.background picture-uri 'file:///usr/share/themes/Adwaita/backgrounds/stripes.jpg'
it doesn't exist unless you have gnome-themes-standard installed.
The 2 workarounds are:
1/ change that key to a valid URI (still starting with file://)
or
2/ install gnome-themes-standard
The real fix is to change the default value to match an existing Ubuntu theme.
as discussed on irc, it's because of the default background value:
$ gsettings get org.gnome. desktop. background picture-uri //usr/share/ themes/ Adwaita/ backgrounds/ stripes. jpg'
'file:/
it doesn't exist unless you have gnome-themes- standard installed.
The 2 workarounds are:
1/ change that key to a valid URI (still starting with file://)
or
2/ install gnome-themes- standard
The real fix is to change the default value to match an existing Ubuntu theme.