The last upgrade of GNOME Flashback Metacity session went fine, but the desktop doesn’t want to start itself. Tested with Lightdm only, as it is the Sparky’s default session manager.

You can fix it in few ways:

Easy way:
Make full system upgrade, then run APTus-> Desktop-> GNOME Flashback to reinstall all the desktop settings.

Manual way:
Create ‘.xinitrc’ file in your home directory and paste the line into the file:
exec /usr/lib/gnome-flashback/gnome-flashback-metacity

Fresh installation:
A fresh Sparky installation via MinimalGUI/CLI iso image (+ Sparky Advanced Installer) provides the fix automatically.

Edit:
It doesn’t make any change.