newcomer, thanks for your advice. Are you sure that this is necessary on my system?
orinoco@jake:~$ LANG=C apt policy systemd-sysv systemd-sysv
Installed: 232-22
Candidate: 232-22
Version table:
*** 232-22 500
500 http://httpredir.debian.org/debian unstable/main amd64 Packages
100 /var/lib/dpkg/status
orinoco@jake:~$ LANG=C apt policy systemd-shim
systemd-shim:
Installed: (none)
Candidate: 10-3
Version table:
10-3 500
500 http://httpredir.debian.org/debian unstable/main amd64 Packages
But I found the reason why it worked.
I've booted my computer with one monitor (dvi -> second display) till sddm pops up without thinking about it. Ctrl+Alt+F1 worked. Horray. Than I switched the second monitor (display-port -> main-display) on. Ctrl+Alt+F1 still worked, even with plasma-shell. Horray again.
But when I wrote about this success, I haven't recognized this circumstances.
Today booted my computer with both monitors switched on and? Ctrl+Alt+F1 didn't work. Ahhh.
But than I realized the monitor thing and reproduced it with success. I will check this in the other direction, too.
jyp, can you repeat my way, please?