I’m certainly sorry to hear that this has been a frustrating experience. I even reached out internally, and we are seeing things work successfully internally. There are tools like “juju debug-log” that can help diagnose what is going wrong, and you can reach out to us on irc freenode.net #juju if you want a bit more live interaction.
The current error that I see (juju-2.9 development) if you specify a series that the charm itself doesn’t support is:
$ juju deploy . --series groovy
ERROR series "groovy" not supported by charm, supported series are: bionic,focal,xenial,trusty
So that is what it would look like if something like ‘etcd’ did not declare support for focal. And there isn’t a lot that would be logged, because we would not allow you to start the application if it doesn’t declare support for it. (You can override this with juju deploy foo --series X --force but we require force because there is limited expectation that an arbitrary charm will know how to configure the application on an arbitrary series.)
You can also supply “–debug” to the deploy command, eg juju deploy foo --debug which will log what the client is trying to do. Because you’ve been editing it out, it is unclear which application is actually failing to deploy.