如题：
vagrant up 启动时一直提示 remote connection disconnect retrying!
但是貌似有时候又可以启动 不知道为什么
remote connection disconnect retrying
我刚刚又重启了下
The guest machine entered an invalid state while waiting for it
to boot. Valid states are 'starting, running'. The machine is in the
'unknown' state. Please verify everything is configured
properly and try again.
If the provider you're using has a GUI that comes with it,
it is often helpful to open that and watch the machine, since the
GUI often has more helpful error messages than Vagrant can retrieve.
For example, if you're using VirtualBox, run `vagrant up` while the
VirtualBox GUI is open.
The primary issue for this error is that the provider you're using
is not properly configured. This is very rarely a Vagrant issue.
然后他提示出了这些语句，然后我再vagrant ssh 发现又能进去了。。。怎么回事？