My VM is inaccessible. Runtime error opening NS_ERROR_FAILURE (0x80004005)

[computermaniac]

There's a problem about removing the guest from the media manager.
As you can see in the attached image below, there seem to be missing the guest .vdi or simply there isn't showing any.

What do I have to do to solve this?

[mpack]

What problem? If the media manager doesn't show media as registered, it isn't registered.

Incidentally: I note that you have an exclamation warning on the CD/DVD tab, not the tab you are showing.

[computermaniac]

What problem? If the media manager doesn't show media as registered, it isn't registered.

Incidentally: I note that you have an exclamation warning on the CD/DVD tab, not the tab you are showing.

Never mind the CD/DVD tab, how do I register media now?

[mpack]

You don't register media using the media manager, you add media using the Storage panel of the settings for whatever VM needs the media. Select a controller on the left, those choose media for it on the right.

The media manager gives you collective information about all media attached to a VM - but you first have to attach it to a VM.

[indepth6]

I am having the same issue about 4 years later. I cannot copy the *.vdi files, since I don't have enough space. What do I do then?