update fails post upgrade

[deckspace]

Details:

• Date | Tue Jan 27 22:59:15 GMT 2026
• DietPi version | v8.25.4 (MichaIng/8)
• Image creator | DietPi Core Team
• Pre-image | Debian mini.iso
• Hardware | Native PC (x86_64) (ID=21)
• Kernel version | Linux redbridgediet 4.19.0-27-amd64 #1 SMP Debian 4.19.316-1 (2024-06-25) x86_64 GNU/Linux
• Distro | buster (ID=5)
• Command | apt-get -y update
• Exit code | 100
• Software title | DietPi-Update

Steps to reproduce:

1. ...
2. ...

Expected behaviour:

• ...

Actual behaviour:

• ...

Extra details:

• ...

Additional logs:

Hit:1 https://deb.debian.org/debian bullseye InRelease
Hit:2 https://deb.debian.org/debian bullseye-updates InRelease
Hit:3 https://deb.debian.org/debian-security bullseye-security InRelease
Ign:4 https://deb.debian.org/debian bullseye-backports InRelease
Hit:5 https://download.docker.com/linux/debian bullseye InRelease
Err:6 https://deb.debian.org/debian bullseye-backports Release
  404  Not Found [IP: 151.101.130.132 443]
Reading package lists...
E: The repository 'https://deb.debian.org/debian bullseye-backports Release' does not have a Release file.

[Joulinar]

You are running very old Debian Buster System. We dropped Support for Buster 2 years ago. Strange enough, your system is reporting Buster while your source files showing Bullseye. What exactly you have done?

[MichaIng]

So it was a Buster system, hence moved to 8 compat branch. Then upgraded to Bullseye. I see, our guide is missing the step to remove the backports suite, which is not available anymore for Bullseye since a while:

sudo sed -i '/bullseye-backports/d' /etc/apt/sources.list

EDIT: I also updated the script in the compat branch to not add backports anymore when a (new) APT mirror is applied.