Since the latest update, GUI does not start anymore

The laptop now starts in a tty1 cli session.
when I log in, and type startx, kde starts, and I have to type my password also in kwallet, to activate wifi.

I tried to edit the grub menu by replacing the quit parameter by `, but it still starts up in the tty1 session.

I also tried adding a custom entry in the grub menu, but that does not help either
To add this to the grub menu: - copy the first grub menu entry from /boot/grub/grub.cnf into the file /etc/grub.d/40_custom

- replace the quit command by `

  • change the menuentry title
    and run sudo update-grub

Any ideas on how to restore normal booting in graphical mode ?