客户一台PVE 6.3版本，按官方教程无法升级到7.x，以下记录一下升级步骤
PVE 6.3 upgrade to 6.4-15 先升级到6.x最高版本
# echo "deb http://download.proxmox.com/debian/pve buster pve-no-subscription" > /etc/apt/sources.list.d/pve-install-repo.list
# wget http://download.proxmox.com/debian/proxmox-ve-release-6.x.gpg -O /etc/apt/trusted.gpg.d/proxmox-ve-release-6.x.gpg
# apt update && apt dist-upgrade
确认升级到6.4-15后再升级到7.x
升级7.x可以按官方教程
# pve6to7 --full
# apt update
# apt upgrade
# sed -i 's/buster\/updates/bullseye-security/g;s/buster/bullseye/g' /etc/apt/sources.list
# echo "deb https://enterprise.proxmox.com/debian/pve bullseye pve-enterprise" > /etc/apt/sources.list.d/pve-enterprise.list
# echo "deb http://download.proxmox.com/debian/ceph-octopus bullseye main" > /etc/apt/sources.list.d/ceph.list
# apt update
# apt dist-upgrade
# apt remove linux-image-amd64
以上就是整个升级过程所有命令，按命令一步一步执行就是了，不排除你升级的时候会有错误，这里不排错。