Vagrant causing XCP-ng VM (with Nested Virtualization ON) to abruptly reboot

Am experiencing a weird behavior and wondering if anybody experienced something similar or has some hints/guidance about it.

On a server running XCP-ng, VMs (running Ubuntu 18.04) with nested virtualization ON are rebooting abruptly when Vagrant (2.2.14) is trying to bring up a libvirt/kvm “sub-guest” machine (NO issue if the machine uses QEMU rather… although too slow for the purpose!). The last line logged by vagrant before the XCP-ng VM restarts itself are something like:

==> vagrant-5-project-2-concurrent-0-job-681: Creating shared folders metadata...
==> vagrant-5-project-2-concurrent-0-job-681: Starting domain.
==> vagrant-5-project-2-concurrent-0-job-681: Error when updating domain settings: undefined method `strip' for nil:NilClass
==> vagrant-5-project-2-concurrent-0-job-681: Waiting for domain to get an IP address...
==> vagrant-5-project-2-concurrent-0-job-681: Waiting for SSH to become available...

The VM just blows up and it reboots. It was working fine until some time ago. t looks like an update of XCP-ng might have broken it.

Anyone experiencing similar problems?
Is anyone able to provide some advice?

Thanks… (for making it to the end of the post… paraphrasing Tom)

Nice Touch!

That is not a behavior I have come across, but I have also done very little testing at all with nested virtualization on XCP-NG. Perhaps posting this in their forums might help.

Thanks Tom, much appreciated!

Will post on the XCP-ng forum too (eventually reporting back here for your users)