LightDM broke for me after this update, though LightDM itself hasn’t been updated at all.
Here is the log, it’s a core dump: Journal from last boot - Pastebin.com
I installed SDDM in the mean time to be able to use my desktop again.
See also this thread for reference: After today's update my machine is stuck on loading lightdm, no TTY access possible either
Update: My issue was that for some reason libpixbufloader-svg.so got renamed to libpixbufloader_svg.so. This broke LightDM and also various GTK apps. No idea how this happened…
Further reference: 2.58.90: -/_ switch in the name of the pixbuf loader? (#1075) · Issues · GNOME / librsvg · GitLab