How to find issue with log report

Hello community,
I use Openhab 2.5.3-1 on a Raspberry 4 with EnoceanPi and Openhab running on external harddisk. Also MQTT via separate (but on same PI) Mosquito broker.
But I guess, I just made somewhere a simple programming mistake… I get the below error message in the log file and dont know the meaning neither how and where to start searching.

Could someone out there please give me an hint?

Thanks a lot,
Haegges

2020-07-03 19:22:23.938 [ERROR] [ersey.server.ServerRuntime$Responder] - An I/O error has occurred while writing a response message entity to the container output stream.
org.glassfish.jersey.server.internal.process.MappableException: org.eclipse.jetty.io.EofException
at org.glassfish.jersey.server.internal.MappableExceptionWrapperInterceptor.aroundWriteTo(MappableExceptionWrapperInterceptor.java:92) ~[?:?]
at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162) ~[bundleFile:?]
at org.glassfish.jersey.message.internal.MessageBodyFactory.writeTo(MessageBodyFactory.java:1130) ~[bundleFile:?]
at org.glassfish.jersey.server.ServerRuntime$Responder.writeResponse(ServerRuntime.java:711) [bundleFile:?]
at org.glassfish.jersey.server.ServerRuntime$Responder.processResponse(ServerRuntime.java:444) [bundleFile:?]
at org.glassfish.jersey.server.ServerRuntime$Responder.process(ServerRuntime.java:434) [bundleFile:?]
at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:329) [bundleFile:?]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) [bundleFile:?]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) [bundleFile:?]
at org.glassfish.jersey.internal.Errors.process(Errors.java:315) [bundleFile:?]
at org.glassfish.jersey.internal.Errors.process(Errors.java:297) [bundleFile:?]
at org.glassfish.jersey.internal.Errors.process(Errors.java:267) [bundleFile:?]
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317) [bundleFile:?]
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305) [bundleFile:?]
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154) [bundleFile:?]
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473) [bundleFile:?]
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427) [bundleFile:?]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388) [bundleFile:?]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341) [bundleFile:?]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228) [bundleFile:?]
at com.eclipsesource.jaxrs.publisher.internal.ServletContainerBridge.service(ServletContainerBridge.java:76) [bundleFile:?]
… and many more…

There is some more info needed to help you out.
What was the latest event that happened? Or did you switch something.