mkdir /mnt/iso mount -t iso9660 -o loop /var/lib/vz/template/iso/proxmox-ve_7.3-1.iso /mnt/iso nano /etc/apt/sources.list.d/ nano /etc/apt/sources.list.d/pve-enterprise.list deb [trusted=yes] file:///mnt/iso/ bullseye pve deb [trusted=yes] file:///mnt/iso/proxmox/packages/ / apt update & apt dist-upgrade