Pve Upgrade
In place upgrade of Proxmox VE node from 5.4 to 8 something.
Upgrade Debian bullseye -> bookworm
Update apt sources lists releases
sed -i 's/bullseye/bookworm/g' /etc/apt/sources.list
sed -i 's/bullseye/bookworm/g' /etc/apt/sources.list.d/*.sources
Update and upgrade, fix shit in place
apt update && apt-upgrade
mv /etc/kernel/postinst.d/zz-pve-efiboot ~
References: https://forum.proxmox.com/threads/problems-after-upgrading-from-6-x-to-7-4-3.125079/ https://forum.proxmox.com/threads/problems-after-6-to-7.131754/