Error! Could not locate dkms . conf file. File: does not exist.

Konfigurowanie pakietu linux-image-3.16.0-4-amd64 (3.16.36-1+deb8u1) ...
/etc/kernel/postinst.d/dkms: Error! Could not locate dkms.conf file.
File: does not exist.

 This problem cause old version of virtualbox in /var/lib/dkms
remove virtualbox, clear dkms folder of old virtualbox folder than install virtualbox again

  sudo apt-get remove virtualbox  sudo rm -rf /var/lib/dkms/vboxhost  sudo apt-get install virtualbox

 Basically you should check the timestamps of any directories under /var/lib/dkms that start with either 'vbox' or 'virtual'. If they're fairly old (e.g. > 1 year) then there's a reasonable chance that they might be cruft left over from an old version of VirtualBox. Deciding whether to delete them or not is at your discretion.