12.3 kernel crash after update

From: Christoph Kukulies <kuku_at_kukulies.org>
Date: Tue, 08 Feb 2022 09:47:32 UTC
I did a freebsd-update upgrade -r 12.3-RELEASE from 12.1 and after the first reboot the system crashes.
Looks like it’s got to do with VBox somehow. 

I uploaded a screenshot to:

https://www.dropbox.com/s/kgmfmuu41ne3yoz/IMG_2426.jpg?dl=0 <https://www.dropbox.com/s/kgmfmuu41ne3yoz/IMG_2426.jpg?dl=0>

I booted into single user, finding that /boot/loader.conf is 0 bytes.

Any clues what I might do from here?

—
Christoph