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user105939
Asked: 2021-10-18 23:35:57 +0800 CST

after Ubuntu 21.10 upgrade: "cannot attach cgroup program" operation not permitted

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Right after upgrading a Ubuntu 21.04 to 21.10, I got this issue: Chromium/Firefox won't start. The error(seen in terminal) is:

$ firefox
cannot attach cgroup program: Operation not permitted
snap

4 Answers

  1. In Ubuntu 21.10, systemd is being switched to the “unified” cgroup hierarchy (cgroup v2) by default instead of (cgroup v1) in previous releases. Please see the Impish Indri Release Notes

    After upgrading, apparmor does not seem to be allowing mounting cgroups version 2 FS which prevents snap based applications from starting properly.

    This, however, might be solved by running this command in the terminal:

    sudo dpkg-reconfigure apparmor

    Select ok when prompted without adding anything.

    If that did not work or for some reason you need to keep the legacy cgroup v1 hierarchy, you can select it via this kernel parameter systemd.unified_cgroup_hierarchy=0 at boot time and wait until snap is updated with full support for (cgroup v2).

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  2. Best Answer

    Is it possible that you are using a Linux kernel that doesn't properly support the unified cgroup hierarchy? I had the same problem as you and it turned out that my GRUB was loading an ancient kernel, instead of a current one.

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  3. I just had the same issue after dist-upgrading from 20.04 to 22.04 - kernel was not updated, so I was still using 5.4.0-89 or 5.4.0-90. Installed 5.15.0 manually using Synaptic, then sudo update-grub and reboot.

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  4. It seems like your upgrade failed to install latest kernel version (i.e 5.10 or so). Use uname -r to comfirm your kernel version and run

    sudo apt install linux-headers-amd64 linux-image-amd64

    To isntall latest image

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