Comment # 14 on bug 1049830 from Gabriele Tettamanzi

(In reply to Larry Finger from comment #13)
> The correct command to rebuild the guest kernel modules is
> sudo /sbin/vboxguestconfig
> That script does all the housekeeping such as installing the prerequisite
> packages, etc.
> 
> Scripts from Oracle sources are not supported, but there should be no need
> to lock anything and manually build the kernel modules unless you are
> running a non-standard kernel in your guest.

Thank you for the explanation.

However:

* the scripts from Oracle were working well on 42.2, they are working no more
on 42.3

* I ran these Oracle stuff when updating Virtualbox;

* on 42.2 I needed to lock out some packages that were interfering with the
updated kernel. modules.