I dug up my upgrade transcript, and it shows, after the first apt-upgrade $ apt full-upgrade
Some packages could not be installed... ... Die folgenden Pakete haben unerfüllte Abhängigkeiten: libc6-dev : Beschädigt: libgcc-8-dev (< 8.4.0-2~) aber 8.3.0-6 soll installiert werden ... i.e. the installation candidate for libc6-dev had a "Breaks" on libgcc-8-dev (< 8.4.0-2~) but 8.3.0-6 was to be installed. I just checked and libgcc-8-dev is only present in buster (8.3.0-6), but not in bullseye. I then "solved" it by removing libgcc8-dev which removed almost all of KDE which I then reinstalled without problems. Normally (in my pbuilder chroot with less packages installed) apt full-upgrade will remove libgcc-8-dev. It seems some package on my system still wanted libgcc-8-dev. I assume it was just a temporary problem, maybe caused by an incomplete migration of packages to testing. From my part, the bug can be closed. Johannes
