If you’ve restored from backup on OS X and are seeing this message when you issue vagrant up:
The VirtualBox VM was created with a user that doesn't match the current user running Vagrant. VirtualBox requires that the same user be used to manage the VM that was created. Please re-run Vagrant with that user. This is not a Vagrant issue. The UID used to create the VM was: 503 Your UID is: 2612
Vagrant is lying. There’s a file in the directory where you’re trying to start the Vagrant box named .vagrant/machines/default/virtualbox/creator_uid; the UID of the creator is in that file. Change it to your current UID and everything will be fine again.