[SOLVED] Differencing child hard disks error...HELP!

[csgpatrick]

I restarted my Windows 7 host after doing a proper shutdown of all my VirtualBox guest OSes. After the reboot, one of my guest machines is now inaccessible with the error:

Failed to open virtual machine located in C:/Users/administrator/VirtualBox VMs/PlanCheck1/PlanCheck1.vbox.

Hard disk 'C:\Users\administrator\VirtualBox VMs\PlanCheck1\Snapshots/{2edc5ebc-4e71-4be5-aa0e-b99317bb8391}.vmdk' with UUID {2edc5ebc-4e71-4be5-aa0e-b99317bb8391} cannot be directly attached to the virtual machine 'PlanCheck1' ('C:\Users\administrator\VirtualBox VMs\PlanCheck1\PlanCheck1.vbox') because it has 1 differencing child hard disks.

Result Code: E_FAIL (0x80004005)
Component: Machine
Interface: IMachine {5eaa9319-62fc-4b0a-843c-0cb1940f8a91}
Callee: IVirtualBox {c28be65f-1a8f-43b4-81f1-eb60cb516e66}


I have tried updating to the latest virtualbox release, with no avail. I need to get this machine back up and running, as it is a production server. Please help!

[csgpatrick]

Problem FIXED!

I went in and edited the XML .vbox file with Notepad++ and removed reference to the offending child snapshot in the <HardDisk> listing, making sure to re-line up the close </HardDisk> afterwords. Seems like such a simple fix now in hindsight. I hope this little posting helps the next guy that has one too many snapshots on their Vbox guest.

[intech_guy]

This was the first hit on google for this issue. my update is based on VirtualBox version 4.1.14 on windows, but I presume the error would be resolved in the same fashion on other platforms. I took a more trivial approach that required no file editing.

In my case I had recently re-integrated a snapshot into my VM. I'm fairly certain it had been running fine after re-integration, but for some reason this time it prevented booting with the same "1 differencing child hard disks." issue.
I was initially puzzled because I had no reference to the child disk in my host's xml config when I looked at it.

I took a look at the Virtual Media Manager and low and behold: there was a [+]against my VM's hard disk (in my case a VHD), with a missing child hanging off it. I deleted the child reference and booting went peachy.

A scary problem to have, but an easy one to solve.

[wcndave]

Problem FIXED!

I went in and edited the XML .vbox file with Notepad++ and removed reference to the offending child snapshot in the <HardDisk> listing, making sure to re-line up the close </HardDisk> afterwords. Seems like such a simple fix now in hindsight. I hope this little posting helps the next guy that has one too many snapshots on their Vbox guest.

This helped me too, more than 8 years later!! I was about ready to give up and start from scratch on a box that had been carefully built!

[mpack]

The OPs post is not a general solution, in fact I have my doubts that it really worked for him in the long term. If VirtualBox tells you it can't do something, or something is missing, it ain't lying. Suppressing the messenger doesn't fix the problem, it just moves the problem elsewhere, where it very likely becomes more serious (i.e. significant data loss, including loss of an entire VM).

[kenshoen]

In my case, <HardDisk> definition was not in the vbox file and had to edit $HOME/.config/VirtualBox/VirtualBox.xml. Nevertheless it helped. Thank you for the solution!

[mpack]

See, that's the problem with following 10 year old advice: the <harddisk> section has been removed from VirtualBox.xml since version 4.0.0. If you manually added one back in then you just messed up badly. In fact if you look, that concept of storing a media registry in VirtualBox.xml is so obsolete that even back then the OP doesn't mention doing it that way.