How to release virtual image from snapshot

[Darwood]

How can I release a virtual image from a snapshot please? Every time I load VirtualBox I get the message "One or more disk image files are currently inaccessible...." I click Check and it shows me which Virtual Boxes are using the virtual image (which is no longer accessible) one of which is a snapshot but I can't find a way to release the image from a snapshot. Please help!

[mpack]

"Release a virtual image from a snapshot"... I really don't know what you mean by that. Assuming that "snapshot" in this context refers to a chain of disk difference files, there is no distinction between "virtual image" and snapshot.

The error message means that a file is missing. If you gave me more information on why the file is missing, and where the missing file occurs in the snapshot chain then I might be able to offer better suggestions.

[Darwood]

It's missing because I moved my virtual boxes from a computer which had a d: drive to a new one that doesn't. The VBox has 2 snapshots both of which have the missing image attached. I've tried looking in the VirtualBox.xml but can't see the name or guid of the missing image in their anywhere.

[mpack]

So by "virtual image" you mean the VM? If multiple snapshots have been detached from the VM then the VM is most likely dead - the snapshot VDI files store all disk sector writes since the first snapshot was created. I assume you don't want to lose all that data (*).

Do you still have the snapshot VDI files, and the base VDI?

(*) If you are content to lose all data written since the first snapshot, then just clone the base VDI and create a new VM around the clone.

[Darwood]

No sorry by virtual image I meant an ISO that I had attached at the time the snapshots were taken. Sorry for using confusing terminology! The ISO is no longer available in the stored location so VB keeps complaining but there doesn't seem to be anything I can do about it.

[mpack]

Ok, ways to unregister an ISO.

1. Use File|Virtual Media Manager to Release the ISO.
2. (Experts only)Edit the .vbox file to remove the StorageAttach line from all snapshots, plus delete all entries in the <DVDImages> branch of the media registry.
3. Delete the VM which registers the ISO.
4. (Variation on 3)Clone the base VDI, create a new VM around the clone VDI, then delete the original VM.