wolfi323, thanks so much, that solved the problem. You are right, that it happened after the update, but I wasn’t sure about it.
Here again we have the two sides of the coin: On the one hand I love that we can solve these problems and that there is a helpful community. On the other hand: Why does this has to happen? It locked me out of a productive system for more than a week.
In YaST I found the packages for udev and systemd in version 16.1 marked in red. Would I downgrade these to 12.1?