Comment 1 for bug 1950835

This feels like a case where 2.6 didn't record some sort of information that 2.9 depends on, which we very likely have an upgrade step to sort out for most cases. I have the feeling we missed the case where the underlying 'machine' is a nested KVM guest.

I do believe you can 'juju refresh --force-units' (juju upgrade-charm) to change the content on disk even if the charm is failing a hook. However, that wouldn't necessarily fix the issue about why Juju doesn't know the network information for that unit.