Upgrading from MQTT v1 for v4 - Any precautions before doing so?

I never turned on automatic updates to the MQTT Broker for Hass.io and so it is still at version 1. Now I see that Hassio has a MQTT version 4. Wow.

The change log shows that version 3 did some very interesting changes:

3

  • Use auto setup (discovery) on Home Assistant
  • Publish his service to Hass.io
  • Attach to Home Assistant user system
  • Set anonymous default to false

The last time I did an upgrade that concerned auto discovery (I think it was dealing with Google Chromecast) I got some issues and a bunch of log entry errors. I had to comment out a bunch of stuff in my configuration.yaml file to get everything back.

I suspect the same is going to happen if I upgrade the MQTT broker to version 4. I have a boatload of switches connected the the broker right now and I don’t need a head ache.

Any advanced of upgrade tips you can offer before I do it would be most appreciated!