Comment 11 for bug 1999640

Interesting, I was able to reproduce this issue today.

Started a 20.04 instance. Using juju 2.8.13 client, bootstrapped 2.8.5 and deployed the old ubuntu-plus charm with only bionic as a series. Then did an upgrade of juju which went right to 2.9.42 on the controller. Upgraded the model and tried the refresh.

$ juju upgrade-charm ubuntu-plus --path ./ubuntu-plus
Added charm "local:bionic/ubuntu-plus-1" to the model.
ERROR missing base name or channel not valid (not valid)

 "charm-origin" : {
  "source" : "local",
  "type" : "charm",
  "id" : "local:bionic/ubuntu-plus-0",
  "hash" : "",
  "revision" : 0,
  "platform" : {
   "os" : "ubuntu",
   "series" : "bionic"
  }
 }

Using a 2.9.42 client does not reproduce the problem