Mac OS X 10.14.2

VirtualBox 5.2.22 and 6.0.0

libvirt installed via homebrew

virsh -V

Virsh command line tool of libvirt 4.10.0

See web site at https://libvirt.org/

Compiled with support for:

 Hypervisors: QEMU/KVM VMware VirtualBox ESX Test

 Networking: Remote Bridging

 Storage: Dir

 Miscellaneous: Daemon Secrets Debug

brew services start libvirt

virsh -c vbox:///session list                               

error: failed to connect to the hypervisor

error: internal error: unable to initialize VirtualBox driver API

Unless there's a known issue with Mojave that's escaped me, surely I've done something clueless .. pointers to the FM or otherwise greatly appreciated.