The easiest way to use a box is to add a box from the publicly available catalog of Vagrant boxes. Running vagrant box add ubuntu/trusty64 returns the same error. Once I upgraded Vagrant / Virtual Box, vvv was able to set itself up properly. You can still sign up and create, release and access Vagrant boxes. This is the same functionality that existed previously.
Fixing Vagrant box URL for trusty64. All Vagrant configuration is done here. Note that the version of Vagrant in the Ubuntu 14.04 repositories is too old, and it is incompatible with the libvirt plugin. vagrant up Bringing machine ‘default’ up with ‘virtualbox’ provider.
3. Create a user named vagrant and add it to sudoers group.