How can I force the installation of the Virtualbox Extension pack?
You can try to install the extension pack using the command line:
sudo VBoxManage extpack install <package file>
Some random things to check:
- Virtualbox version and extension pack version must match.
- Files on /usr/lib/virtualbox must be owned by root.
- /usr/lib itself must be owned by root, too as Uri himself find.
It seems to be saying you need to be root, so run it as root, and then install the pack.