MQTT Binding - Openhab 3.0

Don’t use the MQTT System Broker Connection - get rid of it, and use a normal MQTT Broker Thing.

Though I think I’ve mis-read. What does this mean?

You should just be able to bring across your Things files from OH2.5, including the Bridge/Broker Thing definition, and it’ll all work fine assuming you a) have the MQTT Binding installed and b) haven’t also tried to configure something in the OH3 UI too?

Correct - any v1 configurations will no longer work, as v1 Bindings are not supported in OH3.