I seem to be having a similar problem that Patrick posted here & in qubes-issues when creating a whonix disposableVM. I always get:
Failed to save to domain whonix-ws-dvm to /var/lib…
error: internal error: Failed to save domain ‘xx’ with libxenlight
The strange thing is that if I try to create a non-whonix-based dispvm - even straight after this error - it works. It only fails for my whonix-ws & any other whonix based template.
I am trying this on a laptop with only 4GB RAM - on my own laptop what has 12GB - it works. But as I said - if it was a memory issue - why does it work for any non-whonix based template?
Patrick - you seems to have the same error before - did you overcome it??