今天升级了下vbox里的 centos后(yum update)后，出现以下问题：

Failed to mount folders in Linux guest. This is usually because

the "vboxsf" file system is not available. Please verify that

the guest additions are properly installed in the guest and

can work properly. The command attempted was:

mount -t vboxsf -o uid=`id -u vagrant`,gid=`getent group vagrant | cut -d: -f3` vagrant /vagrant

mount -t vboxsf -o uid=`id -u vagrant`,gid=`id -g vagrant` vagrant /vagrant

The error output from the last command was:

/sbin/mount.vboxsf: mounting failed with the error: No such device

修复方法：

1,sudo /etc/init.d/vboxadd setup

2,yum install virtualbox-guest-utils

vagrant reload后问题完美解决。