vagrantで共有フォルダのマウントに失敗したが未だ解決出来ない

##現状

CentOS7.2
CakePHP3.x系
で環境構築を行なっています。

そこでVagrantfileに共有フォルダを記載して

config.vm.synced_folder "./", "/vagrant", owner: 'vagrant', group: 'apache', mount_options: ['d    mode=777', 'fmode=666']

Vagrantを再起動したところ

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 bug in Vagrant and is usually caused by a faulty
Vagrant box. For context, the command attempted was:

mount -t vboxsf -o d    mode=777,fmode=666,uid=1000,gid=48 vagrant /vagrant

The error output from the command was:


Usage:
 mount [-lhV]
 mount -a [options]
 mount [options] [--source] <source> | [--target] <directory>
 mount [options] <source> <directory>
 mount <operation> <mountpoint> [<target>]

Options:
 -a, --all               mount all filesystems mentioned in fstab
 -c, --no-canonicalize   don't canonicalize paths
 -f, --fake              dry run; skip the mount(2) syscall
 -F, --fork              fork off for each device (use with -a)
 -T, --fstab <path>      alternative file to /etc/fstab
 -h, --help              display this help text and exit
 -i, --internal-only     don't call the mount.<type> helpers
 -l, --show-labels       lists all mounts with LABELs
 -n, --no-mtab           don't write to /etc/mtab
 -o, --options <list>    comma-separated list of mount options
 -O, --test-opts <list>  limit the set of filesystems (use with -a)
 -r, --read-only         mount the filesystem read-only (same as -o ro)
 -t, --types <list>      limit the set of filesystem types
     --source <src>      explicitly specifies source (path, label, uuid)
     --target <target>   explicitly specifies mountpoint
 -v, --verbose           say what is being done
 -V, --version           display version information and exit
 -w, --rw, --read-write  mount the filesystem read-write (default)

 -h, --help     display this help and exit
 -V, --version  output version information and exit

Source:
 -L, --label <label>     synonym for LABEL=<label>
 -U, --uuid <uuid>       synonym for UUID=<uuid>
 LABEL=<label>           specifies device by filesystem label
 UUID=<uuid>             specifies device by filesystem UUID
 PARTLABEL=<label>       specifies device by partition label
 PARTUUID=<uuid>         specifies device by partition UUID
 <device>                specifies device by path
 <directory>             mountpoint for bind mounts (see --bind/rbind)
 <file>                  regular file for loopdev setup

Operations:
 -B, --bind              mount a subtree somewhere else (same as -o bind)
 -M, --move              move a subtree to some other place
 -R, --rbind             mount a subtree and all submounts somewhere else
 --make-shared           mark a subtree as shared
 --make-slave            mark a subtree as slave
 --make-private          mark a subtree as private
 --make-unbindable       mark a subtree as unbindable
 --make-rshared          recursively mark a whole subtree as shared
 --make-rslave           recursively mark a whole subtree as slave
 --make-rprivate         recursively mark a whole subtree as private
 --make-runbindable      recursively mark a whole subtree as unbindable

For more details see mount(8).

このようなエラーが発生しました。

なので、(Vagrantで共有フォルダのマウントに失敗するときの対処方法)[https://qiita.com/ozawan/items/9751dcfd9bd4c470cd82]
こちらを参考にして、解決しようと思ったのですが、vagrant vbguest --statusこのコマンドを実行したら、[default] GuestAdditions 5.2.12 running --- OK.このように返ってきたので、vagrant-vbguestは問題ないと判断し、次にboxの状態を確認しました。

すると、使用しているboxが

centOS7-2        (virtualbox, 0)

このような状態だったので、アップデートをかけようと思い、vagrant box updateを実行したら

==> default: Checking for updates to 'centOS7-2'
    default: Latest installed version: 0
    default: Version constraints: 
    default: Provider: virtualbox
The box 'centOS7-2' is not a versioned box. The box was added
directly instead of from a box catalog. Vagrant can only
check the versions of boxes that were added from a catalog
such as from the public Vagrant Server.

このようなエラーが返ってきました。

何故こうなったのか全く分からないのですが、ここを解決すべき点だと判断したのですが、一向に解決策がわかりません。

##質問事項