So I was having issues with deploying Ubuntu 18 guests on a Xen hypervisor. It originally started with a template for bionic not existing.
This is easily fixed with a couple of commands to copy the karmic.d template to bionic.d template.
However, once your host boots up. You’re now faced with a network issue as Ubuntu 18 added netplan as the default network manager.
This is fixed by replacing the /usr/share/xen-tools/40-setup-networking file with a new xen-tools 4.8 release.
Here is the github comment.
You can simply do the above to fix your issue, or install the latest 4.8 xen-tools at https://github.com/xen-tools/xen-tools/releases
Or you could just grab the 4.8 ubuntu package from eoan Ubuntu 19.10 at http://mirrors.kernel.org/ubuntu/pool/universe/x/xen-tools/xen-tools_4.8-1_all.deb