Pre-requirement:
1. Backup all VM
2. Shutdown and hibernate those VM
Start the upgrade:
1. echo "deb http://download.proxmox.com/debian/pve trixie pve-no-subscription" > /etc/apt/sources.list.d/pve-no-subscription.list
2. apt update
3. apt full-upgrade
Reboot to activate the new Kernel, to check if you got all packages, run 'pveversion -v' and compare your output (all packages should have equal or higher version numbers):
Reference:
https://forum.proxmox.com/threads/pve-9-1-1-to-9-2.184054/
