I upgraded a virtualbox from lubuntu 17.10 to 18.04. On reboot, X doesn't start, though I can enter the console via -F1. Attempting to restart doesn't result in anything obviously interesting in
which I have included below.There is console message when I run
systemctl restart display-manager, though, `[drm:vbox_bo_unpin [vboxvideo]]
EDIT: I removed the diagnostic output; please see the answer below.