Enabling no-subscription repositories

On Debian v13 (trixie)

mv /etc/apt/sources.list.d/pve-enterprise.sources  /root

Create new file

nano /etc/apt/sources.list.d/pve-no-subscription.list 

repos

deb http://download.proxmox.com/debian/pve trixie pve-no-subscription

Adjust Debian repos

nano /etc/apt/sources.list.d/debian.sources 

repos

Types: deb
URIs: http://deb.debian.org/debian
Suites: trixie trixie-updates
Components: main contrib non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

Types: deb
URIs: http://security.debian.org/debian-security
Suites: trixie-security
Components: main contrib non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

Verify repositories declaration

apt policy

Do APT update

apt update

List packages ready for update, most important that there are new packages from PVE repo.

apt list --upgradable

Perform upgrade (when needed)

apt upgrade