juju tells me to "update" to earlier version

[Jordan Barrett]

When you run a Juju 3 client with a Juju 2 controller, you get the following error:
```
ERROR juju client with major version 3 used with a controller having major version 2 not supported
update your juju client to match the version running on the controller
```
However, my client is already a later version than the controller, so updating is not going to help bridge the gap. What should we recommend here instead? Update the controller?

[Ian Booth (wallyworld)]

No, as of right now, you need to refresh your snap from the 2.9 track to match the controller version.

Although 2.9 clients are currently compatible with 3.0 controllers, as 3.0 evolves, this may not remain the case, ie we won't guarantee future 3.x controllers will stay compatible with 2.9 cli clients.

Things like migration, status, upgrades can be run with a 2.9 client though to help ease the transition.

[Jordan Barrett (barrettj12)]

Okay, so we should change the error message to say "downgrade your juju client" ?

[Ian Booth (wallyworld)]

We should perhaps tell people to refresh their snap from the relevant track.

[Andrei Fer (andreifer20)]

snap info juju -> to see all the channels and the current(installed) version
You can switch channel with the snap refresh command:
sudo snap refresh --channel=2.9/stable juju

Verify:
snap info juju -> you will see "2.9/stable" as current version

[John Puskar (jpuskar-amtrust)]

How do we do this if we're on a mac and using brew? I can't figure out how to brew downgrade since the 2.9x isn't tracked in the tap.

[Ian Booth (wallyworld)]

This issue has been fixed
https://github.com/juju/juju/pull/15676