Proxmox 7 upgrade error CT does not support running in a unified cgroup v2 layout
When upgrading Proxmox to ver 7 and running Centos 7.9 as Container it gives error
At least one CT (174) which does not support running in a unified cgroup v2 layout.
To solve it, update systemd using this repo
wget https://copr.fedorainfracloud.org/coprs/jsynacek/systemd-backports-for-centos-7/repo/epel-7/jsynacek-systemd-backports-for-centos-7-epel-7.repo -O /etc/yum.repos.d/jsynacek-systemd-centos-7.repo
yum update systemd