FWIW this also results in Evolution breaking on the Ubuntu MATE live
image. There are multiple bug reports about this.

If enabling the profiles is too drastic, maybe it's possible to disable
the AppArmor user namespace restrictions on the live ISO using `echo 0 |
sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns` during
live image boot, as described in the release notes
(https://discourse.ubuntu.com/t/ubuntu-24-04-lts-noble-numbat-release-
notes/39890#security-improvements).

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https://bugs.launchpad.net/bugs/2065088

Title:
  AppArmor profiles allowing userns not immediately active in 24.04 live
  image

Status in apparmor package in Ubuntu:
  Confirmed

Bug description:
  Side issue from <https://github.com/ValveSoftware/steam-for-
  linux/issues/10843>. I saw this with Steam, but Ubuntu 24.04's
  AppArmor setup for Steam is quite simple, so I suspect that the same
  thing might happen for any of the other third-party software that
  needs an AppArmor profile for
  <https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/2046844>.

  Steps to reproduce:

  1. Boot an Ubuntu 24.04 live image, in a virtual machine with lots of RAM (I 
gave it 8G) so that it will have enough space on the root tmpfs to install 
Steam. Using Debian 12's libvirt and qemu, I found that virtio graphics didn't 
work, and used qxl as a workaround.
  2. When prompted, choose a keyboard layout etc., and choose to "Try Ubuntu" 
rather than "Install Ubuntu".
  3. Open a terminal
  4. sudo dpkg --add-architecture i386
  5. sudo apt update
  6. sudo apt install steam (in this case steam is a transitional package with 
a dependency on steam-installer, both at version 1:1.0.0.79~ds-2)
  7. steam
  8. See a prompt warning me that Steam is proprietary binary-only software. 
Choose Install.
  9. See a light grey progress bar "Steam setup / Updating Steam runtime 
environment...". Wait.
  10. See a dark grey progress bar "Steam / Updating Steam... Downloading 
update (xxx of 465,450 KB)...". Wait.
  11. Dark grey progress bar becomes "Steam / Updating Steam... Extracting 
package...". Wait.
  12. Output in terminal shows "Restarting Steam by request...". Wait.

  Expected result:

  - /etc/apparmor.d/steam allows Steam to create new user namespaces, etc.
  - Steam starts successfully

  Actual result:

  - A dialog box with "Error / Steam now requires user namespaces to be enabled"
  - Audit log: apparmor="DENIED" operation="userns_create" class="namespace" 
info="Userns create restricted - failed to find unprivileged_userns profile" 
error=-13 profile="unconfined" pid=... comm="srt-bwrap" 
requested="userns_create" denied="userns_create" target="unprivileged_userns"

  Workaround:

  - Force Ubuntu's AppArmor profile for Steam to be reloaded: sudo 
apparmor_parser -Tr /etc/apparmor.d/steam
  - Run steam again

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