Vagrant was unable to mount VirtualBox shared folders. This is usually
because the filesystem "vboxsf" is not available. This filesystem is
made available via the VirtualBox Guest Additions and kernel module.
Please verify that these guest additions are properly installed in the
guest. This is not a bug in Vagrant and is usually caused by a faulty
Vagrant box. For context, the command attempted was:
mount -t vboxsf -o uid=1000,gid=1000 home_vagrant_labs /home/vagrant/labs
The error output from the command was:
mount: unknown filesystem type 'vboxsf'
解决办法：
vagrant plugin install vagrant-vbguest
如果在安装过程中出现如下错误：
Vagrant failed to load a configured plugin source. This can be caused
by a variety of issues including: transient connectivity issues, proxy
filtering rejecting access to a configured plugin source, or a configured
plugin source not responding correctly. Please review the error message
below to help resolve the issue:
Errno::EHOSTUNREACH: Failed to open TCP connection to gems.hashicorp.com:443 (No route to host - connect(2) for "gems.hashicorp.com" port 443) (https://gems.hashicorp.com/specs.4.8.gz)
Source: https://gems.hashicorp.com/
建议科学上网
解决方案来自：https://www.cnblogs.com/xishuai/p/macos-use-vagrant-with-virtualbox.html