我也有同样的问题。我认为问题可能是SSH密钥(错误的文件定位或其他东西，但我检查了很多次)，但你可能总是在配置部分添加用户名和密码(不使用SSH密钥)和运行gui，所以Vagrantfile中的代码应该看起来或多或少如下:

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|

  config.ssh.username = "vagrant"
  config.ssh.password = "vagrant"

   config.vm.provider "virtualbox" do |vb|
     vb.gui = true
   end
end

In my case even if GUI was displayed I got black screen (no errors or possibility to login or anything else) and in console I got the Error: Connection timeout. Retrying... many times. I made sure I had VT-x (virtualization) enabled in BIOS, I checked many combinations of versions of both Virtual Box and Vagrant together and many Vagrant boxes (for some of them I didn't have black screen in GUI but still have connection problems). Finally I've updated VirtualBox and Vagrant again to the last versions and the problem still occurred.

最关键的是在运行vagrantup(使用Vagrantfile中的GUI)后，在VirtualBox中查看图标，如下图所示

虽然我在VirtualPC中没有错误(没有VT-x未启用的警告)，但我的V图标是灰色的，所以这意味着VT-x被禁用。正如我说的，我一直在我的BIOS中启用它。

Finally I realized the problem might by HYPER-V which I also installed and enabled to test sites on older Internet Explorer. I went to Windows Control Panel -> Programs and functions / Software and choose from the menu on left Turn on or Turn off Windows functions (hope you will find those, I use Polish Windows so don't know exact English names). I turned off Hyper-V, restarted PC and after running Virtual Box and vagrant up I finally had no errors, in GUI I have login screen and my V icon stopped to be gray.

我浪费了很多时间来解决这个问题(和许多电脑重启)，所以我希望这可能对任何在Windows上有问题的人有帮助-确保你在控制面板中关闭了Hyper-V。

删除文件:

C:\Users\UserName\\.vagrant.d\insecure_private_key

然后运行:

vagrant up

It used to help to switch to trusty32, but the situation now got worse again: I tried to use Homestead 2.0 and now I've got the Connection Timeout problem again, which would't usually be a problem, because switching to 32bit helped before. But now I can't just add a line like config.vm.box="ubuntu/trusty32" because we don't have a classic Homestead.yaml file anymore, the values in the new 2.0 Homestead.yaml file just seem to be inserted into the real one in the background and there ist no Vagrantfile available that I could manually edit ...

希望有人能帮忙……

我的运行正常，然后这个“警告:远程连接断开。一遍又一遍——大概20遍——直到连接上。基于以上的答案，我只是

vagrant destroy
vagrant up

一切都很好。我的很简单，但我把Vagrantfile压缩到config.vm.box = "ubuntu/trusty64"，它还在运行。这就是为什么毁灭然后重新开始似乎是最好的选择。鉴于这些流浪汉图像的无国籍性质，我不明白为什么在每个情况下都不会奏效。我刚刚开始研究这个问题，我可能会发现这不是真的。

我在《Vagrant 1.6.5》和《Virtual Box 4.3.16》中也遇到了同样的问题。 在https://github.com/mitchellh/vagrant/issues/4470上描述的解决方案对我来说很好，我只需要删除VirtualBox 4.3.16并安装旧版本4.3.12。

我在VirtualBox中运行vagrant/VirtualBox时得到了这个。我通过在主机上运行流浪机器来解决这个问题。