vagrant up报错问题

vagrantfile如下：

Vagrant.configure("2") do |config|
    config.vm.define :master1, primary: true do |master|
        master.vm.provider "virtualbox" do |v|
            v.customize ["modifyvm", :id, "--name", "hadoop-master1", "--memory", "512"]
       end
       master.vm.box = "centos72-hadoop"
       master.vm.hostname = "hadoop-master1"
       master.vm.network :private_network, ip: "192.168.10.10"
    end

   (1..2).each do |i|
    config.vm.define "slave#{i}" do |node|
        node.vm.box = "centos72-hadoop"
        node.vm.hostname = "hadoop-slave#{i}"
        node.vm.network :private_network, ip: "192.168.10.1#{i}"
        node.vm.provider "virtualbox" do |vb|
          vb.memory = "1024"
        end
     end
   end

  #manage hosts file 
  config.hostmanager.enabled = true
  config.hostmanager.manage_host = true
  config.hostmanager.manage_guest = true

   #provision
   config.vm.provision "shell", path: "init.sh", privileged: false
end

vagrant up
报错如下：

C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/response.rb:70:in `block in <class:Response>': undefined method `downcase' for nil:NilClass (NoMethodError)
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/response.rb:68:in `each'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/response.rb:68:in `inject'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/response.rb:68:in `<class:Response>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/response.rb:16:in `<module:SFTP>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/response.rb:3:in `<module:Net>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/response.rb:3:in `<top (required)>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/request.rb:2:in `<top (required)>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp/session.rb:5:in `<top (required)>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/net-sftp-2.1.2/lib/net/sftp.rb:2:in `<top (required)>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/vagrant-2.2.4/plugins/communicators/ssh/communicator.rb:12:in `<top (required)>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/mingw64/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/vagrant-2.2.4/plugins/communicators/ssh/plugin.rb:14:in `block in <class:Plugin>'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/vagrant-2.2.4/lib/vagrant/registry.rb:27:in `get'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/vagrant-2.2.4/lib/vagrant/machine.rb:259:in `communicate'
        from C:/zjsw/HashiCorp/Vagrant/embedded/gems/2.2.4/gems/vagrant-2.2.4/lib/vagrant/action/builtin/wait_for_communicator.rb:16:in `block in call'