I'm trying to create differencing image based on differencing image in VirtualBox 4.2.18. Official documentation says it should be possible: http://www.virtualbox.org/manual/ch05.html#diffimages Basically I want to achieve this drive hierarchy: + immutable image with Debian and all software installed +---- differencing image with specific configuration, autoreset=off, readonly +-------- differencing image with autoreset=on +---- another differencing image for different virtual machine +-------- differencing image with autoreset=on I successfully created differencing image based on differencing image, but I'm not able to connect it to virtual machine :( It always shows error: Failed to open the hard disk .... cannot register hard disk ... because hard disk with UUID ... already exists Here is screenshot of Virtual Media Manager and error dialog Virtual Media Manager Window screenshot Very strange is that the new differencing image (tempdrive.vdi) doesn't have Actual Size 0. I wasn't able to connect it, but still, it has 36KB of data on it... This is very similar to this older question: How to create a chained differencing disk of another differencing disk in Virtual Box? but suggested solution is not working anymore in VirtualBox 4.2.18, so I posted it as a new question. (Limit for posting links and screenshots is quite annoying..)