Open Windows PowerShell with adminstrator rights, enter:
$ VBoxManage setextradata YOURVMNAME VBoxInternal2/SharedFoldersEnableSymlinksCreate/YOURSHAREFOLDERNAME 1
Check if it got set:
$ VBoxManage getextradata YOURVMNAME enumerate
Inside the same PowerShell with administrator rights enter:
$ VBoxManage sharedfolder add YOURVMNAME --name "YOURSHAREFOLDERNAME" --hostpath "\\?\C:\PATH\TO\YOUR\SHARED\FOLDER\ON\WINDOWS"
Create a new folder for the mount:
$ mkdir /PATH/TO/NEW/FOLDER
Open:
$ sudo nano /etc/rc.local
Inside the file before the exit 0 enter:
# Mount shared folder
/sbin/mount.vboxsf YOURSHAREFOLDERNAME /PATH/TO/NEW/FOLDER vboxsf
Save and reboot your VM.
Sometimes, after a new version of VirtualBox or debian updates, you need to reinstall the GuestAdditions and run sudo m-a prepare
and sudo apt-get install build-essential linux-headers-
uname -r dkms
to install the new linux headers that somehow get lost sometimes...
You're welcome - good to know that it helped & worked!