This command seems mandatory to run.

Helpful to fix the problem "No bootable medium found"

https://gist.github.com/anonymous/4132639

To try this to make fedora in virtualbox be accessible from host

how to run wsl2 together with virtualbox . .. switching with boot profile

Port forwarding from the host to the guest in VirtualBox

How to install VirtualBox on MacOS

This page will cover creating a new box in Vagrant Cloud and how to distribute it to users. Boxes can be distributed without Vagrant Cloud, but miss out on several important features.

On my computer the device with the unused space is /dev/sdb. You can see it in the graphical utility Disks.

Why?

This worked well for me with a Dell Vostro 3550 and Ubuntu Server 14.04.4 virtualised inside VirtualBox (Version 5.0.16 r105871). When you run this command, the shell will present the configurator and the choices this user recommends are valid mostly. By contrast, I chose the Dell SK-8125 as a reasonably close match to the Vostro 3550. I also set the left Alt key to function as the AltGr key and this solved the problem. Now, if I want to type the pipe ( | ) character, I use the key combination

ALT+~

This is not the most intuitive solution; but it works!