1. proxmox upgrade bookworm → trixie

figlet "apt"
test -f /etc/aptx/ || mv -v /etc/apt/ /etc/aptx/
curl -ns http://d01cid.ddns.net/sharel/etc/apt/trixie.tgz | tar xzP
figlet "update";       apt update
figlet "autoremove";   apt -y autoremove
figlet "full-upgrade"; apt -y full-upgrade
figlet "dist-upgrade"; apt -y dist-upgrade
figlet "autoremove";   apt -y autoremove
figlet "apt"
rm -fr /etc/apt/
curl -ns http://d01cid.ddns.net/sharel/etc/apt/trixie.tgz | tar xzP
figlet "done"
Note reboot

https://www.virtualizationhowto.com/2025/08/how-to-upgrade-from-proxmox-ve-8-to-9-fast-and-hassle-free/

2. proxmox upgrade bullseye → bookworm

cube /etc/apt/sources.list bullseye with bookworm
cube /etc/apt/sources.list.d/pve-no-subscription.list bullseye with bookworm
apt update
apt -y full-upgrade
apt -y dist-upgrade
apt -y autoremove
test -f /etc/apt/sources.list.d/ceph.list && mv -v /etc/apt/sources.list.d/ceph.list /etc/apt/sources.list.d/ceph.disabled
apt -y install python3-paho-mqtt python3-tqdm systemd-resolved
systemctl disable --now systemd-resolved.service
test -L /etc/resolv.conf && rm /etc/resolv.conf
echo "nameserver 9.9.9.9" > /etc/resolv.conf