Upgrading Marvel

Hi,
At our site we're running elasticsearch and marvel 2.1.2. Do they have to be upgraded in lock-step with one another? Or could we upgrade marvel directly to 2.3.2 independent of ES?

Regards,
David

Ah, I see that this is addressed in the release notes....

For those who are also looking for upgrade information:
https://www.elastic.co/guide/en/marvel/2.3/installing-marvel.html#upgrading