Error in HomeAssistent Add-on

Continuing the discussion from Error starting zigbee2mqtt:

I’ve just had this error causing the add-on to become non-responsive. This is new to me but I have just updated the controller firmware. Running 0.116.2.

Supervisor error

Oct 17 21:06:09 hassio hassio-supervisor[1979]: 20-10-17 20:06:09 ERROR (MainThread) [supervisor.api.ingress] Ingress error: Cannot connect to host ssl:default [Connection refused]

Add-on log

2020-10-17T21:07:20: PM2 log: App [npm:0] starting in -fork mode-
2020-10-17T21:07:20: PM2 log: App [npm:0] online
> zigbee2mqtt@1.15.0 start /zigbee2mqtt-1.15.0
> node index.js
Zigbee2MQTT:info  2020-10-17 21:07:23: Logging to console and directory: '/share/zigbee2mqtt/log/2020-10-17.21-07-23' filename: log.txt
Zigbee2MQTT:info  2020-10-17 21:07:24: Starting Zigbee2MQTT version 1.15.0 (commit #1.15.0)
Zigbee2MQTT:info  2020-10-17 21:07:24: Starting zigbee-herdsman...
Zigbee2MQTT:error 2020-10-17 21:07:25: Error while starting zigbee-herdsman
Zigbee2MQTT:error 2020-10-17 21:07:25: Failed to start zigbee
Zigbee2MQTT:error 2020-10-17 21:07:25: Exiting...
Zigbee2MQTT:error 2020-10-17 21:07:25: Error: Error while opening serialport 'Error: Error: No such file or directory, cannot open /dev/ttyACM0'
    at Znp.<anonymous> (/zigbee2mqtt-1.15.0/node_modules/zigbee-herdsman/dist/adapter/z-stack/znp/znp.js:136:32)
    at (<anonymous>)
    at /zigbee2mqtt-1.15.0/node_modules/zigbee-herdsman/dist/adapter/z-stack/znp/znp.js:27:71
    at new Promise (<anonymous>)
    at __awaiter (/zigbee2mqtt-1.15.0/node_modules/zigbee-herdsman/dist/adapter/z-stack/znp/znp.js:23:12)
    at SerialPort.<anonymous> (/zigbee2mqtt-1.15.0/node_modules/zigbee-herdsman/dist/adapter/z-stack/znp/znp.js:134:49)
    at SerialPort._error (/zigbee2mqtt-1.15.0/node_modules/zigbee-herdsman/node_modules/@serialport/stream/lib/index.js:198:14)
    at /zigbee2mqtt-1.15.0/node_modules/zigbee-herdsman/node_modules/@serialport/stream/lib/index.js:242:12
npm ERR! errno 1
 ERR! zigbee2mqtt@1.15.0 start: `node index.js`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the zigbee2mqtt@1.15.0 start script.
npm ERR!
 This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2020-10-17T20_07_25_170Z-debug.log
2020-10-17T21:07:27: PM2 log: App [npm:0] exited with code [1] via signal [SIGINT]