As I posted somewhere about changing the Gnome policykit patch before, it happend again.
It means, Debian devs revert the patch back to the old one.
So, if you use tiny window managers, installed via Sparky APTus-> Desktop tool, or via Sparky minimal iso - you should change the policykit command, stored in the wm startup script, from:
/usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1It happens in the mw's: awesome, bspwm, enlightenment, fluxbox, i3, icewm, jwm, openbox, pekwm, trinity, windowmaker.
Otherwise, upgrade your system and re-run APTus-> Desktop-> your desktop icon to make it easy.