I installed Variety background changer in my machine, setup the option Make sure that wallpapers set by Variety will be used on the login screen and works flawlessly for many weeks.
I am not sure if was an update or I launch in recovery mode, one time, but now, when I turn-on my laptop, LightDM appear with my users for login but only with the generic background /usr/share/backgrounds/warty-final-ubuntu.png. I deactivate Variety and setup backgrounds from $HOME/Pictures folder but the problem remains.
I have setup with dynamic backgrounds in lightdm, I put these commands to check this:
sudo su
xhost +SI:localuser:lightdm
su lightdm -s /bin/bash
and after this i check variables:
lightdm@banshee:~$ gsettings get com.canonical.unity-greeter draw-user-backgrounds
true
lightdm@banshee:~$ gsettings get com.canonical.unity-greeter background
'/usr/share/backgrounds/warty-final-ubuntu.png'
lightdm@banshee:~$ gsettings set org.gnome.settings-daemon.plugins.background active true
I imagine that the last one is always the default value, but the first one setup that lightdm setup the user background that is setup, but always appears the default background in my login, my $HOME partition is not encrypted, Some other thing that i need to review?
P.D. afther the commands that i put above, lightdm appears with default background and i get the variables with gsettings but the last one, appears false
lightdm@banshee:~$ gsettings get org.gnome.settings-daemon.plugins.background active
false
well, searching a little more today in Ask Ubuntu I found a similar problem with Trusty already resolved, I check their best answer and this was the problem in my case too! :)
Now I saw that this best answer was based in another answer for a question that was for 12.04, so both ones, one for precise and the another one for trusty, solve my problem in xenial :)