Lightdm caughts signal 10 from Xorg

[Yanpas]

When I lock my session with lightlocker - lightdm (in 2nd attempt) stops responding. Blank screen on tty8, warning that session is locked on tty7. If i use gnome-screensaver: Press lock, then I see lockscreen of gnome-screensaver. When I press switch user - lightdm stops respondong, blank screen again (You need to repeat it twice).
Attaching logs. In ANOTHER lightdm.log process 5330 is Xorg

[Yanpas (yanpaso)]

The problem began to appear when I turned on "Automatically lock the session". It seems to me that no matter it is locked when the screensaver is activated or deactivated.

[Yanpas (yanpaso)]

The bug appears on my netbook after hibernate. If I hibernate it 2-3 times, after one of them I do not see lightdm-gtk-greeter, I see only black screen. The only solution is to sudo service lightdm restart.