I just updated Vagrant / VirtualBox and started getting weird errors whenever I tried to interact with the Vagrant environment. All the errors seemed to be API errors similar to “Error in API call to get_state”.

This seems to be due to VirtualBox not being able to access some of it’s machines. The fix is to open the GUI and remove the ones that are marked as “Inaccessible”.

The issue wasn’t caused by the upgrade, it was purely because I removed some of the boxes directly from the disk instead of doing it through VirtualBox.