upgrade-charm --switch failure message is not clear

[Stuart Bishop]

upgrade-charm --switch is supposed to "Crossgrade to a different charm", but is refusing with an error:

$ juju upgrade-charm --switch . juju-ingest
ERROR cannot upgrade "ubuntu-basenode" to "juju-ingest"

The error is not helpful, as it is not telling me *why* it cannot upgrade. I believe I meet all the criteria, or I wouldn't be attempting the operation.

[Stuart Bishop (stub)]

(in this case, the source charm contains no configuration at all and the only relation being participated in is juju-info with its subordinate units, so all documented criteria are met)

[Dmitrii Shcherbakov (dmitriis)]

Seems similar to https://bugs.launchpad.net/juju/+bug/1783983

[Richard Harding (rharding)]

Agreed on the related link. The thing is we allow upgrading the same charm mysql->mysql using different charms but not changing from one charm "ubuntu-basenode" to another charm "juju-ingest".

We can take this as feedback that the error about the different charm names wasn't clear though and make that a better message.

[Canonical Juju QA Bot (juju-qa-bot)]

This bug has not been updated in 2 years, so we're marking it Low importance. If you believe this is incorrect, please update the importance.