Proxmox from v6 to v7 error when starting LXC:
WARN: old systemd (< v232) detected, container won’t run in a pure cgroupv2 environment! Please see documentation → container → cgroup version.
Edit the grub on the Proxmox 7 server.
Searches for the parameter
and add the fallow config
The line need to look:
Then save and in the command line
start and connect one
This probably causes the CGroup version to be set back to version 1. PVE7 seems to only use version 2.
Also another Solution is to either install new systemd or migrate your machine to CentOS8 or something newer
For more help ask Proxmox support