upgrade-model failed for develop stream

[Yang Kelvin Liu]

Upgrade model to a develop stream for a specific build number failed even the controller has already been upgraded.

$ juju upgrade-controller --agent-stream=develop
best version:
    2.8-beta1.1

$ juju status --relations --color --storage -m k1:controller
Model Controller Cloud/Region Version SLA Timestamp
controller k1 microk8s/localhost 2.8-beta1.1 unsupported 00:22:50-07:00

$ juju upgrade-model -m t1 --agent-stream=develop
best version:
    2.8-beta1.1
ERROR model cannot be upgraded to 2.8-beta1.1 while the controller is 2.8-beta1: upgrade 'controller' model first

[John A Meinel (jameinel)]

(note that in this case, I think the issue is that the upgrade-controller command "succeeds" because the client can find the binary, but the controller itself cannot upgrade because the model's agent-stream isn't pointed at the stream that the client looked at. And so the controller hasn't actually upgraded, which is why you cannot upgrade the model.)

[John A Meinel (jameinel)]

'juju status' also isn't helpful here, because it reports the "requested agent version" as the overall controller version. You need to do "juju show-machine -m controller 0" or "juju status -m controller --format=yaml" to see that the individual controller machines aren't at the new version.