Dear Ben, thanks alot! Installing these packages from backports (firmware-misc-nonfree, firmware-intel-sound, firmware-iwlwifi, xserver-xorg-video-intel and the linux headers+image 4.5.0-0) did the trick with Jessie.
I had some minor graphical problems like the black shadow above the controlbar at the bottom not recovering after a dialogue opened and closed again. And some software seemed to be buggy with new versions in stretch so I tried again to upgrade/dist-upgrade into testing after maken a safety image of root. At first it failed to start kwin (fatal error - same like everytime before) but finally I found out that the package task-kde-desktop was not installed (only task-desktop task-german-desktop and task-german-kde-desktop) Installing it did the trick and resulted in a working Stretch. I am thinking wether the not installed task-kde-desktop should be filed as a bug as well (I used the netinst iso). But I don't know how to file a bug for that iso. Thanks again! Maria Ben Hutchings: > On Wed, 2016-05-04 at 21:38 +0200, Maria wrote: >> Package: src:linux >> Version: 4.5.1-1~bpo8+1 >> Severity: important >> >> Dear Ben, >> >> I didn't find the error among the list of over 1500 packages shown to >> me, sorry. This is an addendum to error #823156 which I wrote >> initially on this topic. And the title of #819272 sounded similar. >> I actually reinstalled Debian on a USB 3 Harddisk to test wether the >> problem still occurs with the Firmware (firmware-misc-nonfree, >> firmware-intel-sound, firmware-iwlwifi). > > The firmware-iwlwifi version is too old; you'll need the version in > jessie-backports. > >> But I still get stuck at the console. >> Kwin still refuses to load and aborts with the same fatal error. > > You didn't say what the error is. > > Which version of xserver-xorg-video-intel do you have? You may need > the version from jessie-backports. > >> I actually started with the install of the new header files and >> kernel. As I had the same effect I started with installing the >> firmware-misc-nonfree. >> Then I installed the other two. But there was no change. Just an >> error of failing to load some Kernel module, which was too fast to >> see. I hope it is in the logs below. > > I don't see it, unfortunately. > > Ben. >