Comment 1 for bug 1818197

I wonder what the config netplan generate complained about.

If you can set a password on your snapshot image, you'll be able to login even when cloud-init fails.

This will get you a shell inside your image:

sudo mount-image-callback --system-mounts /path/to/qcow2-snapshot -- chroot _MOUNTPOINT_ /bin/bash

From there, you can run passwd and set the root pw for the image,

Then boot via qemu, and if it fails, you can login on console with the set password.

From there, running: 'cloud-init collect-logs' and attaching the file would be useful for debugging.

If you are in there, looking at /etc/netplan/50-cloud-init.yaml and re-running netplan --debug generate to see the error and attach that as well.