Zigbee2mqtt running but 502 bad gateway

My HA instance has been working for some time now (a year+) and I never had problems with Zigbee2mqtt - it worked.
As of today, it doesn’t anymore. No config or hardware changes, no errors in logs, device ( SONOFF Zigbee 3.0 USB Dongle Plus V2 on /dev/ttyACM0) is detected and visible in “system”). It might have been an auto-update that broke it.

The only thing I saw in logs was a warning to move from EZSP to EMBER. Tried that (changed in config), it starts and runs - but I still have 502 error on Zigbee2mqtt interface.

This is the latest zigbee2mqtt restart log, everything looks OK:

[08:54:10] INFO: Starting Zigbee2MQTT...

Starting Zigbee2MQTT without watchdog.

[2024-12-04 08:54:11] info: z2m: Logging to console, file (filename: log.log)

[2024-12-04 08:54:11] debug: z2m: Loaded state from file /config/zigbee2mqtt/state.json

[2024-12-04 08:54:11] info: z2m: Starting Zigbee2MQTT version 1.42.0 (commit #unknown)

[2024-12-04 08:54:11] debug: z2m: sd-notify loaded

[2024-12-04 08:54:11] info: z2m: Starting zigbee-herdsman (2.1.9)

[2024-12-04 08:54:11] debug: z2m: Using zigbee-herdsman with settings: '"{\"network\":{\"panID\":6754,\"extendedPanID\":[221,221,221,221,221,221,221,221],\"channelList\":[11],\"networkKey\":\"HIDDEN\"},\"databasePath\":\"/config/zigbee2mqtt/database.db\",\"databaseBackupPath\":\"/config/zigbee2mqtt/database.db.backup\",\"backupPath\":\"/config/zigbee2mqtt/coordinator_backup.json\",\"serialPort\":{\"path\":\"/dev/ttyACM0\",\"adapter\":\"ember\"},\"adapter\":{\"disableLED\":false}}"'

[2024-12-04 08:54:11] debug: zh:adapter: Path '/dev/ttyACM0' is valid for 'EmberAdapter'

[2024-12-04 08:54:11] info: zh:ember: Using default stack config.

[2024-12-04 08:54:11] debug: zh:controller: Starting with options '{"network":{"networkKeyDistribute":false,"networkKey":"HIDDEN","panID":6754,"extendedPanID":[221,221,221,221,221,221,221,221],"channelList":[11]},"serialPort":{"path":"/dev/ttyACM0","adapter":"ember"},"adapter":{"disableLED":false},"databasePath":"/config/zigbee2mqtt/database.db","databaseBackupPath":"/config/zigbee2mqtt/database.db.backup","backupPath":"/config/zigbee2mqtt/coordinator_backup.json"}'

[2024-12-04 08:54:11] info: zh:ember: ======== Ember Adapter Starting ========

[2024-12-04 08:54:11] info: zh:ember:ezsp: ======== EZSP starting ========

[2024-12-04 08:54:11] info: zh:ember:uart:ash: ======== ASH Adapter reset ========

[2024-12-04 08:54:11] info: zh:ember:uart:ash: RTS/CTS config is off, enabling software flow control.

[2024-12-04 08:54:11] debug: zh:ember:uart:ash: Opening serial port with {"path":"/dev/ttyACM0","baudRate":115200,"rtscts":false,"autoOpen":false,"parity":"none","stopBits":1,"xon":true,"xoff":true}

[2024-12-04 08:59:11] debug: z2m: Saving state to file /config/zigbee2mqtt/state.json

And mosquito broker display connect…disconnect:

2024-12-04 09:01:10: New connection from 172.30.32.2:37050 on port 1883.
2024-12-04 09:01:10: Client <unknown> closed its connection.

Does anyone have any ideas how to make it work? Again - it worked and stopped working by itself with no changes in conf / HW.

Version info:

* Core 2024.11.3
* Supervisor 2024.11.4
* Operating System 13.2
* Frontend 20241106.2

Zigbee2mqtt: 1.42.0-2 (Changelog) 
Mosquitto broker: 6.4.1

This is normal. Can you show you zigbee2mqtt configuration.yaml file please.

Sure, here’s my config (hope that’s the right file):

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:
  base_topic: zigbee2mqtt
  user: mqtt_user
  password: .mqttp4ss.
  server: mqtt://192.168.99.19:1883
  include_device_information: true
  keepalive: 60
  version: 5
serial:
  port: /dev/ttyACM0
  adapter: ember
advanced:
  adapter_concurrent: null
  transmit_power: 20
  channel: 11

Is that the whole file? Comparing to mine and you are missing some.

frontend:
  port: 8099

and

homeassistant: true

Oh, thanks… the file in the post above is from Addons->Zigbee2mqtt->config (yaml view).
Looking /homeassistant/zigbee2mqtt/configuration.yaml in file editor, the file “configuration.yaml” is different:

homeassistant: true
mqtt:
  server: mqtt://192.168.99.19:1883
  user: mqtt_user
  password: .mqttp4ss.
  discovery: true
  broker: 192.168.99.19
  birth_message:
    topic: hass/status
    payload: online
  will_message:
    topic: hass/status
    payload: offline
serial:
  port: /dev/ttyACM0
  adapter: ezsp
frontend:
  port: 8099
advanced:
  homeassistant_legacy_entity_attributes: false
  legacy_api: false
  legacy_availability_payload: false
  log_level: debug
device_options:
  legacy: false
  retain: true
devices:
(list of devices)