Snap/Apparmor stopped working in Ubuntu 22.04

I can no longer update snap apps on Ubuntu 22.04. If I try to refresh firefox I get:

$ sudo snap refresh firefox
error: cannot perform the following tasks:
- Setup snap "firefox" (2277) security profiles (cannot setup profiles for snap "firefox": cannot load apparmor profiles: exec: "apparmor_parser": executable file not found in $PATH
apparmor_parser output:
)

Even downloading basic Hello World gets me:

$ sudo snap install hello-world
error: cannot perform the following tasks:
- Setup snap "core" (14447) security profiles (cannot setup profiles for snap "core": cannot create host snap-confine apparmor configuration: cannot reload snap-confine apparmor profile: cannot load apparmor profiles: exec: "apparmor_parser": executable file not found in $PATH
apparmor_parser output:
)

Snap used to work fine then suddenly stopped with these issues. My versions are:

$ snap --version
snap    2.57.6
snapd   2.57.6
series  16
ubuntu  22.04
kernel  5.15.0-58-generic

$ apparmor_parser --version
AppArmor parser version 3.0.4
Copyright (C) 1999-2008 Novell Inc.
Copyright 2009-2018 Canonical Ltd.

I checked that the apparmor_parser executable is reachable from $PATH and it is:

$ which apparmor_parser
/usr/sbin/apparmor_parser
$ echo "$PATH"
/home/user/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/usr/bin:/snap/bin:/home/user/.local/bin

At this point I am out of ideas what the problem is and how I can fix it. I tried reinstalling everything but it still did not solve the issue. Can anyone please help?

had the same issue. fixed it by reinstalling AppArmor (and rebooting)

sudo apt reinstall --purge apparmor