during the openhab startup I get always this error
java.lang.NullPointerException: null
at org.openhab.binding.mqtt.generic.MqttChannelTypeProvider.derive(MqttChannelTypeProvider.java:132) ~[?:?]
at org.openhab.binding.mqtt.homeassistant.internal.discovery.HomeAssistantDiscovery.publishResults(HomeAssistantDiscovery.java:248) ~[?:?]
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) [?:?]
But I don’t have any Homeassistant in my environment what should I do?
Firstly, this is a warning so it’s not something that is causing problems. It’s safe to ignore.
The error is coming from some problem during scanning for Home Assistant MQTT topics. Since you don’t have any devices publishing using the HA MQTT standard, this further confirms that this warning can be ignored.
There was a PR some time ago to correct this (or something like this). What version of OH are you running?