Public bug reported:
This happened during an "apt dist-upgrade".
Just in case error log is not part of the bug report here it goes:
$ cat /var/lib/dkms/virtualbox/6.1.10/build/make.log
DKMS make.log for virtualbox-6.1.10 for kernel 5.8.0-34-generic (x86_64)
mié 06 ene 2021 12:31:28 -03
make: Ent
Thank you gwel! With your message I realized I did not have VirtualBox
installed from the expected source because I installed "virtualbox"
instead of "virtualbox-6.1":
$ apt-cache policy virtualbox
virtualbox:
Installed: 6.1.10-dfsg-1~ubuntu1.20.04.1
Candidate: 6.1.10-dfsg-1~ubuntu1.20.04.1