After migrating BE 4.x project to 5.x and running inference engine shows following error for any HTTP request sent to an HTTP channel.

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<TimeStamp> <Engine_Name>
Fatal [HTTP_Core_Listener_Thread] - [driver.http] I/O dispatch worker terminated abnormally org.apache.http.nio.reactor.IOReactorException: I/O dispatch worker terminated abnormally at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.execute(AbstractMultiworkerIOReactor.java:356) at com.tibco.cep.driver.http.server.impl.httpcomponents.HttpCoreAsyncServer$1.run(SourceFile:368) Caused by: java.lang.IllegalArgumentException: Null action at java.nio.charset.CharsetDecoder.onMalformedInput(CharsetDecoder.java:383) at org.apache.http.impl.nio.NHttpConnectionBase.(NHttpConnectionBase.java:162) at org.apache.http.impl.nio.DefaultNHttpServerConnection.(DefaultNHttpServerConnection.java:100) at org.apache.http.impl.nio.DefaultServerIOEventDispatch.createConnection(DefaultServerIOEventDispatch.java:119) at org.apache.http.impl.nio.DefaultServerIOEventDispatch.createConnection(DefaultServerIOEventDispatch.java:53) at org.apache.http.impl.nio.reactor.AbstractIODispatch.connected(AbstractIODispatch.java:71) at org.apache.http.impl.nio.reactor.BaseIOReactor.sessionCreated(BaseIOReactor.java:240) at org.apache.http.impl.nio.reactor.AbstractIOReactor.processNewChannels(AbstractIOReactor.java:426) at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:288) at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:105) at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:584) at java.lang.Thread.run(Thread.java:748)
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TIBCO BusinessEvents engine using HTTP channel throws error [Caused by: java.lang.IllegalArgumentException: Null action]

All

Check if Advanced tab is missing in HTTP channel in studio. This happens when project is not imported from previous version using (File Import -> TIBCO BusinessEvents -> Existing BusinessEvents Studio Project), instead just loaded into Studio. This corrupts HTTP channel and not migrate into BE 5.x correctly.

Do one of the following to resolve the issue :-

1.) Delete and recreate HTTP channels and configured input destinations or
2.) Import BE 4.x project using "File Import -> TIBCO BusinessEvents -> Existing BusinessEvents Studio Project"