Comment 3 for bug 1638714

Case 1 and 3 is already catered for and messages around these cases seem clear.

For 2, the error comes from a version check at the time when we are trying to set hosted model's agent binary version in state. I'll re-word to a modified version of your suggestion:

ERROR: hosted models cannot be a later version than the controller: 2.0.1 > 2.0.0

However, I think that the major source of confusion is not so much the phrasing of the error message but the fact the user did not upgrade a controller first.

Maybe we need to say:

hosted models cannot be a later version than the controller: 2.0.1 > 2.0.0. Upgrade 'controller' model first.