Error processing MQTT Message/An error occurred whilst transforming JSON expression

  • RPI3
  • Raspbian Stretch 9.11
  • Java 1.8.0_152
  • Openhab 2.5.3-1

Hi All

Not entirely new to linux or OpenHab but struggling to get to the bottom of what I thought was a simple transform error - but finding that I don’t know where to start looking. the message is generic and I have tried turning on what I thought was the right debug logging log:set debug and that didn’t help. I am not sure how to turn on logging specifically for transformations but I don’t know what the source of the error is - so no idea where to start looking in my config files…

/var/log/openhab2/openhab.log shows:

2020-03-21 22:49:42.805 [WARN ] [.mqtt.internal.MqttMessageSubscriber] - Error processing MQTT message.
org.openhab.core.transform.TransformationException: An error occurred while transforming JSON expression.
at org.openhab.core.transform.TransformationHelper$TransformationServiceDelegate.transform( ~[bundleFile:?]
at org.openhab.binding.mqtt.internal.MqttMessageSubscriber.processMessage( [bundleFile:?]
at [bundleFile:?]
at org.eclipse.paho.client.mqttv3.internal.CommsCallback.deliverMessage( [org.eclipse.paho.client.mqttv3-1.1.0.jar:?]
at org.eclipse.paho.client.mqttv3.internal.CommsCallback.handleMessage( [org.eclipse.paho.client.mqttv3-1.1.0.jar:?]
at [org.eclipse.paho.client.mqttv3-1.1.0.jar:?]
at [?:1.8.0_152]

Any help much appreciated - I’ve been looking at this for ages and just struggling with where to look to find my next clue (which item is this? is there a problem with a transform although I only have one and it is for a device which is currently not turned on and thus not sending MQTT messages)

Try restarting OH a few times, allowing it to fully reload between restarts.

sudo systemctl restart openhab2

Normally takes me 1 reboot and 2-3 restarts for OH to start working correctly.

If the above does not work and no device is sending an MQTT message then try commenting out the transformation or uninstall/reinstall the service.