$vagrant up

Bringing machine 'default' up with 'virtualBox' provider...
The Box 'precise32' is still stored on disk in the Vagrant 1.0.x
format. This Box must be upgraded in order to work properly with
this version of Vagrant.

我尝试了vagrant init但也遇到了错误.

$vagrant init precise32 http://files.vagrantup.com/precise32.Box

`Vagrantfile` already exists in this directory. Remove it before
running `vagrant init`.

如何将我的精确32盒升级为新版Vagrant？