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。
如果遇到以下提示：
Fetched 332 MB in 53s (6,217 kB/s)
W: (pve-apt-hook) !! WARNING !!
W: (pve-apt-hook) You are attempting to remove the meta-package 'proxmox-ve'!
W: (pve-apt-hook)
W: (pve-apt-hook) If you really want to permanently remove 'proxmox-ve' from your system, run the following command
W: (pve-apt-hook) touch '/please-remove-proxmox-ve'
W: (pve-apt-hook) run apt purge proxmox-ve to remove the meta-package
W: (pve-apt-hook) and repeat your apt invocation.
W: (pve-apt-hook)
W: (pve-apt-hook) If you are unsure why 'proxmox-ve' would be removed, please verify
W: (pve-apt-hook) - your APT repository settings
W: (pve-apt-hook) - that you are using 'apt full-upgrade' to upgrade your system
E: Sub-process /usr/share/proxmox-ve/pve-apt-hook returned an error code (1)
E: Failure running script /usr/share/proxmox-ve/pve-apt-hook只需编辑 vi /etc/apt/sources.list.d/pve-no-enterprise.list 把 buster 改成 bullseye 即可
#deb http://download.proxmox.com/debian/pve buster pve-no-subscription
deb http://download.proxmox.com/debian/pve bullseye pve-no-subscription