Zigbee2MQTT: MQTT error: connect ECONNREFUSED 127.0.0.1:1883

What it means

Zigbee2MQTT tried to reach the MQTT broker and nothing listens at that address and port.

Why it happens

• The Mosquitto add-on is not installed or not started.
• In HA OS Zigbee2MQTT runs in its own container, so 127.0.0.1 is the container itself, not the broker.
• The broker listens on another port or only with TLS.

How to fix it

1. Install and start the Mosquitto broker add-on.
2. In the Zigbee2MQTT settings use mqtt://core-mosquitto:1883 with a Home Assistant user as login.
3. Check the broker from the browser with the MQTT client (over WebSocket).

Useful tools

/mqtt-websocket-client/

Other Zigbee2MQTT errors

• Error while starting zigbee-herdsman
• Connection Refused: not authorised.