按照入门教程操作到 2.2 章节，cd ~/Homestead && Vagrant provision，执行失败？

如题，按照《laravel 入门教程》操作到2.2章节的时候，在新增了sample项目之后，修改homestead.yaml里的相关配置之后，执行cd ~/Homestead && vagrant provision，报错。然后我搜索了相关报错信息，找到一个方法：rm /etc/udev/rules.d/60-vboxadd.rules；然后再vagrant halt；再vagrant up，vagrant provision；结果还是报错。望大神解答，谢谢！

$ vagrant provision
==> homestead-7: Running provisioner: file...
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: inline script
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: inline script
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: C:/Users/DANDEL~1/AppData/Local/Temp/vagrant-shell20170430-9700-1r1rz1p.sh
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Creating Site: homestead.app
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Creating Site: sample.app
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Restarting Nginx
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Creating MySQL Database
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Creating Postgres Database
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Creating MySQL Database
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Creating Postgres Database
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Clear Variables
==> homestead-7: Running provisioner: shell...
    homestead-7: Running: script: Update Composer
==> homestead-7:                                                                         
==> homestead-7:   [Composer\Downloader\TransportException]                              
==> homestead-7:   The "https://getcomposer.org/versions" file could not be downloaded: Failed to enable crypto
==> homestead-7:   failed to open stream: operation failed                               
==> homestead-7:                                                                         
==> homestead-7:
==> homestead-7: self-update [-r|--rollback] [--clean-backups] [--no-progress] [--update-keys] [--stable] [--preview] [--snapshot] [--] [<version>]
The SSH command responded with a non-zero exit status. Vagrant
assumes that this means the command failed. The output for this command
should be in the log above. Please read the output to determine what
went wrong.