Vagrant was unable to mount VirtualBox shared folders.
$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
default: Guest Additions Version: 5.0.6
default: VirtualBox Version: 6.0
==> default: Mounting shared folders...
default: /mnt/fuelphp => /Users/username/sharedir
Vagrant was unable to mount VirtualBox shared folders. This is usually
because the filesystem "vboxsf" is not available. This filesystem is
made available via the VirtualBox Guest Additions and kernel module.
Please verify that these guest additions are properly installed in the
guest. This is not a bug in Vagrant and is usually caused by a faulty
Vagrant box. For context, the command attempted was: