After Updating from 3.0.0 to 3.0.1 it works all normal. But after some hours i can not send some command to items (over all bindings and over basicUI and mainUI). I can switch an item, but when I reload the page it is on the previous state and the thing itself also receive no command (nothing happens).
After a restart it works, but only for some hours.
I see nothing related to this problem in openhab.log and event.log.
Do you see any errors in the logs?
No, nothing 
Now it happens again. And after a while my log is flood with the following error (many every second):
> 2021-01-29 23:07:35.936 [ERROR] [internal.events.ThreadedEventHandler] - Error on event handling.
> java.lang.NullPointerException: null
> at java.util.concurrent.LinkedBlockingQueue.dequeue(LinkedBlockingQueue.java:214) ~[?:?]
> at java.util.concurrent.LinkedBlockingQueue.poll(LinkedBlockingQueue.java:460) ~[?:?]
> at org.openhab.core.internal.events.ThreadedEventHandler.lambda$0(ThreadedEventHandler.java:60) [bundleFile:?]
> at java.lang.Thread.run(Thread.java:834) [?:?]
I hope this help.
I’ve found out, that influxdb flood the daemon.log and syslog with many entries and the filesize was very big.
To stop that I use the following solution: Disable Influxd logging - InfluxData Community
Maybe this was the problem. I will update you when it happens again.
It works until now.
I think it was a Problem with disk space and has nothing to do with version 3.0.1