Debian 13 new source list file format (deb822)

Since Debian 13 (Trixie) the sources.list file will become obsolete. There is now an error message when you update your packages using sudo apt update --audit

Instead of using the old /etc/apt/sources.list you will have to convert your source list file to the new deb822 file format and drop it to /etc/apt/sources.list.d/debian.sources

You have to convert from this:

# /etc/atp/sources.list
# Debian Stable

deb https://deb.debian.org/debian/ stable main non-free-firmware
deb-src https://deb.debian.org/debian/ stable main non-free-firmware

deb https://deb.debian.org/debian/ stable-updates main non-free-firmware
deb-src https://deb.debian.org/debian/ stable-updates main non-free-firmware

deb https://security.debian.org/debian-security stable-security main non-free-firmware
deb-src https://security.debian.org/debian-security stable-security main non-free-firmware

To this:

# /etc/apt/sources.list.d/debian.sources
# Debian Stable

Types: deb deb-src
URIs: https://deb.debian.org/debian
Suites: stable stable-updates
Components: main contrib non-free non-free-firmware
Enabled: yes
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

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

You can do this yourself or use the command: sudo apt modernize-sources.