APT 3.0 and the deb822 sources format

Debian 13 (Trixie) is the first stable release to ship APT 3.0: clearer columnar output, a new dependency solver, and deb822 debian.sources written by the installer by default.

Debian 13 (Trixie) is the first stable release to ship APT 3.0. It is a major upgrade: source configuration moves to the structured deb822 format (.sources files), command-line output is redesigned, and dependency resolution gets a new solver.

What APT 3.0 changes

Easier-to-read output

Commands like apt update and apt upgrade switch to a columnar layout: installed, upgraded and removed packages are colour-coded and counted in separate columns:

sudo apt update
sudo apt upgrade

No more scanning a single long line — "-44 packages can be upgraded", "3 newly installed" and "1 to remove" each get their own column.

A new dependency solver

APT 3.0 rewrites dependency resolution. It proposes saner solutions for complex conflicts and far less often suggests removing essential packages.

The deb822 sources format

The Debian 13 installer now writes the structured deb822 format to /etc/apt/sources.list.d/debian.sources by default, replacing the one-line sources.list:

# Old one-line format (sources.list)
deb https://deb.debian.org/debian trixie main contrib non-free non-free-firmware

# New deb822 format (debian.sources)
Types: deb
URIs: https://deb.debian.org/debian
Suites: trixie trixie-updates trixie-backports
Components: main contrib non-free non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

deb822 spells every field out as Key: value, keeps comments and groups readable, and drops the trixie/updates slash notation — security updates are simply trixie-security:

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

The old format still works

The one-line /etc/apt/sources.list format remains fully supported in Debian 13; APT reads both formats. Systems upgraded from Debian 12 do not need to migrate right away. Third-party sources (Docker, NVIDIA, etc.) will adopt deb822 over time.

Inspect and adjust your sources

# Show the effective source configuration
apt indextargets | grep -E '^(URI|SUITE|COMPONENTS)' | sort -u

# Refresh indexes after editing
sudo apt update

For mirror selection and regional acceleration see the mirrors page; full source configuration is covered in basic configuration.

Next steps

Package management - everyday apt / dpkg usage
Upgrading from Debian 12 - source changes during upgrade
Debian 13 hub - back to the release overview

New installs should go straight to Debian 13: Download Debian 13 →