Fixing Virtualbox mounting shared folders issue

As a VirtualBox user, I started to encounter recently issues related to mounting shared folders into Linux guest VMs. The usual mount command started to fail with "wrong fs type" error after updating the Virtualbox Guest Additions and I couldn't understand why.

After some research, I found that this was due to the fact that the upgrade script of the Guest Additions was confused by the fact that there were many VBoxGuestAdditions-4.XXX under /opt and it failed to pick up the most recent one in order to create the symbolic link under /usr/lib.

So, in order to solve the issue, you have to manually create symbolic link using the command :

sudo ln -s /opt/VBoxGuestAdditions-4.3.10/lib/VBoxGuestAdditions /usr/lib/.

In the above, "4.3.10" is the latest version of the Guest Additions I installed. Replace it with the correct version in your case (list all the directories under /opt and pickup the latest one starting by VBoxGuestAdditions).