vagrant-vbguest和vagrant-winnfsd安装时报错

Question

vagrant: 2.2.2
VirtualBox:6.0.0-127566

在win10上使用vagrant，安装vagrant-vbguest和vagrant-winnfsd时报错：

λ vagrant plugin install vagrant-vbguest
Installing the 'vagrant-vbguest' plugin. This can take a few minutes...
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:

  SSL_connect SYSCALL returned=5 errno=0 state=SSLv2/v3 read server hello A (https://gems.hashicorp.com/specs.4.8.gz)

Source: https://gems.hashicorp.com/

安装vagrant-winnfsd出现同样的错误。

这是怎么回事呢？