When I log in and start Firefox, my computer crashes. I get back to the lightdm login screen. When I log in for the second time, Firefox runs with no problem.This is what Firefox prints to stderr:firefox-esr: Fatal IO error 17 (File exists) on X server :0.I am using Debian Jessie, I started having this problem after I upgraded a couple of packages from the jessie-backports repo.
xorg crashes when firefox starts
debian;xorg;firefox;backports