All derivates of Ubuntu (Kubuntu, Xubuntu, etc.) are affected by this; online repositories are not. Graphical front-ends that are based on the apt package manager, such as Synaptic and KPackage, are also affected.

The paths for the mount points for mounting discs have been changed in the new Ubuntu version, but this hasn't been accounted for in the apt package manager. The
installation of single packages without any dependencies works fine; however, when installing multiple packages, apt uses a different mode and fails because of those broken mount points.

Workaround:

Open a console window to run the command sudo apt-cdrom add to add a DVD as a installation source.

Create a symlink to the new mount points by typing in:

sudo ln -s /media/<name of the cd-rom drive>/* /cdrom/

or alternatively:

sudo ln -s /media/apt/* /cdrom/

This creates symlinks pointing to the correct paths so the installation can work as normal.