It's at the top of bug 994921. Additionally, or alternatively please uncomment this option from /etc/gdm3/custom.conf:
# Additionally lets the X server dump core if it crashes #Enable=true and reboot. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1769819 Title: Xorg crashes after system sleep / wakeup To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1769819/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
