Even though you have set bidirectional for the option Shared Clipboard in settings ( under General –>Advanced ) some times it will not work. The following steps fixed this issue for me.
In the guest OS do the following :
- update source.list file
- enable the
contribrepositories; e.g. for Debian 8, make sure your
/etc/apt/sources.listcontains something like
deb http://ftp.debian.org/debian jessie main contrib
2. Install guest addition software.
apt-get update apt-get install virtualbox-guest-dkms