Ubuntu The following packages have unmet dependencies: $package1 : Depends: $package2 but it is not going to be installed

I got today the below from recipes that are supposed to configure a brand new desktop:

$ sudo apt-get -q -y -f build-dep virtualbox-ose-guest-utils virtualbox-ose-guest-x11 virtualbox-ose-guest-dkms
...
The following packages have unmet dependencies:
 virtualbox-ose-guest-x11 : Depends: virtualbox-guest-x11 but it is not going to be installed
...

If you add virtualbox-guest-x11 to the installation then you get something else:

$ sudo apt-get -q -y -f install virtualbox-ose-guest-utils virtualbox-guest-x11 virtualbox-ose-guest-x11 virtualbox-ose-guest-dkms
...
The following packages have unmet dependencies:
 virtualbox-guest-x11 : Depends: xorg-video-abi-11
                        Depends: xserver-xorg-core (>= 2:1.10.99.901)
E: Unable to correct problems, you have held broken packages.
...

Just running the below will take care of installing the package and all its dependencies, however be prepared to wait a really long time before all packages are built and installed. You probably do not want to proceed this route and just find absolutely all dependencies by hand. It will depend on your needs:

$ sudo apt-get -q -y -f build-dep virtualbox-ose-guest-utils virtualbox-guest-x11 virtualbox-ose-guest-x11 virtualbox-ose-guest-dkms

The bottom line is that after using build-dep you can now proceed without errors with your install:

$ sudo apt-get -q -y -f install virtualbox-ose-guest-utils virtualbox-guest-x11 virtualbox-ose-guest-x11 virtualbox-ose-guest-dkms