vagrantでmountエラー、Failed to mount folders in Linux guest. This is usually beacuse

解決方法
vboxをリビルドする必要があるようです。
まずsshで入ります
vagrant ssh
リビルド実行します。
sudo /etc/init.d/vboxadd setup

Removing existing VirtualBox non-DKMS kernel modules [ OK ]
Building the VirtualBox Guest Additions kernel modules
Building the main Guest Additions module [ OK ]
Building the shared folder support module [ OK ]
Building the OpenGL support module [失敗]
(Look at /var/log/vboxadd-install.log to find out what went wrong)
Doing non-kernel setup of the Guest Additions [ OK ]

一旦macのコンソールに戻ります。
exit
vagrantを再起動します。
vagrant halt
vagrant up