virtual box 6.0 on Debian 9

Question

I am following this tuto for installing virtual box in Debian, but

# apt-get install virtualbox-6.0
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 virtualbox-6.0 : Depends: libqt5opengl5 (>= 5.0.2) but it is not going to be installed
                  Depends: libqt5printsupport5 (>= 5.0.2) but it is not going to be installed
                  Recommends: linux-image but it is not installable
E: Unable to correct problems, you have held broken packages.

Looks like libqt5opengl5 needs qtbase-abi-5-7-1 ...

# apt-get install libqt5opengl5
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libqt5opengl5 : Depends: qtbase-abi-5-7-1

and qtbase-abi-5-7-1 is provided by libqt5core5a

but I already have libqt5core5a :

# apt-get install libqt5core5a
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libqt5core5a is already the newest version (5.11.3+dfsg-2).
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.

any clue ?

Answer 1

virtual-box 5.0 works without any dependencies issues !

# apt-get install virtualbox-5.0 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  libqt4-dbus libqt4-opengl libqt4-xml libqtcore4 libqtdbus4 libqtgui4 libsdl-ttf2.0-0 qdbus qt-at-spi qtchooser qtcore4-l10n
Suggested packages:
  qt4-qtconfig
Recommended packages:
  linux-headers
The following NEW packages will be installed:
  libqt4-dbus libqt4-opengl libqt4-xml libqtcore4 libqtdbus4 libqtgui4 libsdl-ttf2.0-0 qdbus qt-at-spi qtchooser qtcore4-l10n virtualbox-5.0
0 upgraded, 12 newly installed, 0 to remove and 3 not upgraded.
Need to get 64.5 MB/71.8 MB of archives.
After this operation, 192 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://deb.debian.org/debian stretch/main amd64 libsdl-ttf2.0-0 amd64 2.0.11-3+b1 [18.6 kB]
Get:2 http://download.virtualbox.org/virtualbox/debian stretch/contrib amd64 virtualbox-5.0 amd64 5.0.40-115130~Debian~stretch [64.4 MB]
Fetched 64.5 MB in 53s (1,218 kB/s)  
.........

Answer 2

My first port of call would be to get apt-get to look for any unmet dependencies and fix them using sudo apt-get -f install.

There is a lot more information here about what can cause this, and potential fixes. They say in the link that the -f install option is the simplest and the best one to try, then goes into more detail.