i have the same “problem” as Kamil. with quotes, because everything works.
I guess i need to do some reading to understand the difference between MQTT config under “settings>other services” and MQTT Binding Broker as a Thing.
maybe this will be a good place to start : MQTT System broker Vs. MQTT Embedded broker
EDIT: i realise this page is about embedded vs system broker, which is different from system broker and MQTT binding!
The one under settings is refered as System MQTT broker.
I used a different identifier for each of them to avoid conflict of course. it is the one under Settings>other services that generates the error.
it seems that to be able to add a generic MQTT “generic” thing, i need to have the MQTT binding, but i am confused what is the difference between these two.
also i remember the system broker appearing as a discovered thing at somepoint in oh3.