If a VM was created by another VM that no longer exists, using it as a disposable VM template fails.

[DemiMarie]

How to file a helpful issue

Qubes OS release

R4.2

Brief summary

If a VM (let’s call it “X”) is created by another VM, but the creating VM no longer exists, trying to create a disposable VM based on X fails with a KeyError in qubesd.

Steps to reproduce

1. Use the Admin API to create a VM that has template_for_dispvms set to True. The simplest way to do that is to restore a backup using a disposable VM.
2. Delete the creating VM.
3. Try to use the created VM as a disposable VM template.

Expected behavior

It works.

Actual behavior

qubesd fails with a KeyError. Deleting the created-by-disp-backup-restore tag prevents the KeyError.

[github-actions]

The labels on this issue currently indicate that it affects only Qubes OS 4.2 or earlier. Since Qubes OS 4.2 has reached end of life (EOL), this issue may eventually be closed. If anyone believes that this issue should remain open, please leave a comment saying so. For example, if an issue still affects Qubes OS 4.3, then the comment "Affects 4.3" will suffice.

[DemiMarie]

I believe this affects 4.3.