De handleiding: https://www.debian.org/releases/bookworm/amd64/release-notes/ch-upgrading.en.html#proposed-updates 4.2.9. The proposed-updates section If you have listed the proposed-updates section in your APT source-list files, you should remove it before attempting to upgrade your system. This is a precaution to reduce the likelihood of conflicts. -- In the stairway of life, you'd best take the elevator.