I've just upgraded to Ubuntu 19.10 especially to enable Livepatch. Unfortunately, I get the same error I had with Ubuntu 18.04:
$ sudo canonical-livepatch enable [key]
2019/10/22 17:20:20 error executing enable: Livepatchd error: The platform Ubuntu 19.10 is not supported. exiting.
Does anybody have any clue where the problem could come from?