[AlexanderGrooff]

I've found that AppArmor started to block Firefox:

audit: type=1400 audit(1642063521.864:246): apparmor="DENIED" operation="ptrace" profile="snap.firefox.firefox" pid=9868 comm="Shutdow~minator" requested_mask="trace" denied_mask="trace" peer="snap.firefox.firefox"

I really don't like it, but turning off Apparmor worked for me. Not sure what caused AppArmor to start complaining all of a sudden.

[qiqitori]

Your policy is blocking ptrace from processes that don't seem like they should need ptrace (very few processes need ptrace). So why would Firefox need ptrace? Some cursory googling suggests that ptrace is used for plugins and by the crash reporter.

There are apparmor profiles for Firefox, e.g. this one: https://github.com/nibags/apparmor-profiles/blob/master/appa... Maybe you could add it to your system and see if that fixes things.

[AlexanderGrooff]

This seems to fix it, even though there was already a default apparmor config for Firefox (which looked _very_ familiar).

Thanks!

[glandium]

That smells like the Shutdown Hang Terminator triggering a crash report.