It is a never ending story. New dist release, new problems with Virtualbox.
What is the current problem with a Fedora 30 guest on a Windows host and Virtualbox 6.0.8? Well, the guest additions won’t work, especially
vboxadd.service refuses to start.
After asking my search engine of choice it revealed the libxcrypt to be the culprit. There are some changes mentioned at https://fedoraproject.org/wiki/Releases/30/ChangeSet and it is referenced at https://forums.virtualbox.org/viewtopic.php?f=3&t=92953.
libxcrypt-compat package and the
vboxadd.service will start again, problem fixed.