Zigbee2MQTT onboarding fails to connect

Configuration Zigbee
1

I’ve gone through the setup steps for Zigbee2MQTT over and over and still the same result, and it’s driving me nuts. I have Mosquito installed, MQTT user set up and assigned, HA ZBT-2 connected. I install Zigbee2MQTT and when I submit the onboarding I just get a broken page saying “localhost refused to connect”.

Config:

data_path: /config/zigbee2mqtt
socat:
  enabled: false
  master: pty,raw,echo=0,link=/tmp/ttyZ2M,mode=777
  slave: tcp-listen:8485,keepalive,nodelay,reuseaddr,keepidle=1,keepintvl=1,keepcnt=5
  options: "-d -d"
  log: false
mqtt:
  server: mqtt://core-mosquito:1883
  user: mqtt
  password: MQTT7#Fdlqq11
serial:
  port: /dev/serial/by-id/usb-Nabu_Casa_ZBT-2_E072A1D8AE00-if00
  adapter: ember
  baudrate: 460800
  rtscts: true
force_onboarding: false

Screenshot 2026-08-14 090743
Screenshot 2026-08-14 090743401×231 2.55 KB

2

You’re missing a T. it should be mqtt://core-mosquitto:1883

3

Thank you so much! Why is it always something so simple? I had copy-pasted that from a guide so they must have had a typo.