openHAB 3 System startup with warning

Setup, Configuration and Use Scripts & Rules
1

I use a openHAB 3 installation via openhabian.
I get a WARNING in the openhab.log when restarting the system:

2022-01-10 22:59:26.216 [WARN ] [mmon.WrappedScheduledExecutorService] - Scheduled runnable ended with an exception: 
java.lang.NullPointerException: null
	at org.openhab.binding.zigbee.ember.handler.EmberHandler.setGroupRegistration(EmberHandler.java:365) ~[?:?]
	at org.openhab.binding.zigbee.ember.handler.EmberHandler.initializeDongleSpecific(EmberHandler.java:120) ~[?:?]
	at org.openhab.binding.zigbee.handler.ZigBeeCoordinatorHandler.initialiseZigBee(ZigBeeCoordinatorHandler.java:551) ~[?:?]
	at org.openhab.binding.zigbee.handler.ZigBeeCoordinatorHandler.lambda$2(ZigBeeCoordinatorHandler.java:559) ~[?:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) ~[?:?]
	at java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[?:?]
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) ~[?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
	at java.lang.Thread.run(Thread.java:829) [?:?]

What is the reason?

2

It might well be a proper Zigbee issue you are facing; but if you have recently upgraded to OH3.2 and this is something popping up only at startup, this might be a variant of what is discussed here: