目的 virtual box の バージョン 5.1.20 r114628 にアップデートした際に、 マウントがうまくいかなくなった件ではまったのでメモ。 vagrant up 時の エラー内容 Vagrant was unable to mount VirtualBox shared folders. This is usually because the filesystem "vboxsf" is not available. This filesystem is made available via the VirtualBox Guest Additions and kernel module. Please verify that these guest additions are properly installed in the guest. This is not a b