I am seeing this in the log for a Homie device. System was working fine and then this just popped up. Using MQTT Explorer the Homie device is online and working just fine. Any thoughts?
2019-12-26 15:28:32.281 [hingStatusInfoChangedEvent] - 'mqtt:homie300:Queen:scene-54703' changed from ONLINE to OFFLINE (COMMUNICATION_ERROR): The connection object has not been set. start() should have been called!
How often are you seeing this and have you tried changing the logs to TRACE or DEBUG if error is frequent?
This was the first time - I had to restart OH to make it go away. It’s critical error as all Homie devices went offline when the error occurred.
MQTT experienced a few changes in the time of Nov to Dec and a few continuous integration tests that would catch errors had to be disabled. Please keep observing the log and if possible fill a bug report on Github.
I had the same problem today so I filed an issue on Github.