I have a Windows 10 VM in VirtualBox (Ubuntu 14 host, VirtualBox 5.0.10 platform). It was originally a Windows 7 virtual machine, and Windows 7 was fully activated.

A few days ago, I wanted to run some Windows Updates and install Threshold 2, but I was told that there wasn't enough disk space.

No problem, just resize the disk.... except, that's a problem. I have 2 snapshots (that I don't really care about) of the Windows 10, and my snapshots are preventing the virtual machine from seeing the increased disk size.

When I go to delete the snapshots, I get either of the following messages, depending on which snapshot it is that I'm trying to delete:

  • Hard disk {path-to-disk file} has more than one child hard disk (2). or...
  • Unable to merge storage {path-to-disk file} not enough free storage space.

(I increased the disk size from 45GB up to 60GB using vboxmanage)

So then I read that if I clone the VM, that would essentially get rid of the snapshots for me, and then I could increase the disk size on the cloned VM.

That's what I did as of a few days ago. I then successfully installed Threshold 2.

This evening, as I sat down to do some work, I noticed that Windows was telling me that it wasn't activated. I went into the Settings, and the message was that "Windows 10 isn't activated because the previous version of Windows was never activated."

Fortunately, I had a backed up copy of the old VM (pre-clone, and pre-updating to Threshold 2). I turned that back on, and confirmed that Windows was indeed activated.

Why the heck did Windows 10 lose its activation on the clone that I created? Can I create a clone without Windows losing its activation? If not, how can I delete these snapshots, which are preventing me from resizing the hard disk that Windows uses?


I'm going to answer this, not because my problem with VirtualBox is completely resolved, but for all practical purposes, the problems outlined in this question are resolved. I'm going to open up a new question with my current issue (a segmentation fault whenever I try to delete a snapshot).

  1. I still don't know why Windows loses its activation when the VM is cloned, but I've tested it a 2nd time on a new clone with VirtualBox 5.0.12, and it lost its activation again. That option is obviously not usable.

  2. The first error message, "hard disk has more than 1 child disk", was due to me somehow having a couple different copies of the actual Windows VDI disk file laying around. I can't remember exactly what I did to fix it, but I recall reviewing everything tied to the VM within Settings -> Storage, and also browsing to the VM's path on the host machine and deleting all of the files that weren't actually in use.

  3. The 2nd error message above, "unable to merge storage ... not enough free storage space" is now resolved. That was an issue with the host machine literally not having enough free space on the hard drive.

  • Thanks for the tip in your second point. I had to search the "Virtual Media Manager" to find the extra child disks.
    – palswim
    Oct 3 '17 at 20:24
  • Glad it was helpful. :)
    – David W
    Oct 3 '17 at 22:14

This helped me with the activation issue.

Bascially you need to make sure, that the machine uid keeps the same. You should remove both, the original and the cloned machine in the VirtualBox gui, but keep the files!

Look at the .vbox file of your original machine and copy the machine id to the .vbox file of your clone machine. Afterwards, add the cloned machine with the .vbox file (virtualbox does not allow two machines with the same id) and you shouldn't get a activation error anymore.

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