ClassCastException on JPA Entities after Application Restart - jpa

Question

We're now using WebSphere 9 and some applications are behaving differently then they did in WebSphere 8.5.5.
Every time we restart the apps (not the server), they stop working correctly and the log shows exceptions similar to this one:
java.lang.ClassCastException: pt.sibs.epms.persistence.entity.EpmsDebugParameters incompatible with pt.sibs.epms.persistence.entity.EpmsDebugParameters
It only happens with JPA entities and I've checked the classpath to make sure the Jar is only referenced once (I've exported classloaders info for the application).
I've confirmed that the EntityManagerFactory is being closed when the application stops (via contextDestroyed on a ServletContextListener).
As stated before, this happens only on WebSphere 9, it works well on WebSphere 8.5.5 and GlassFish 4.1.
Any ideas?
EDIT #1
I'm using WebSphere Full Profile and the exception that it's being thrown is:
java.lang.ClassCastException: pt.sibs.epms.persistence.entity.EpmsDebugParameters cannot be cast to pt.sibs.epms.persistence.entity.EpmsDebugParameters
at pt.sibs.epms.util.logging.LoggerConfiguration.<clinit>(LoggerConfiguration.java:40)
at pt.sibs.epms.util.logging.LoggerConfiguration.<clinit>(LoggerConfiguration.java)
at pt.sibs.epms.suppdata.EpmsSuppData.<init>(EpmsSuppData.java:55)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:88)
at sun.reflect.DelegatingConstructorAccessorImpl.__newInstance(DelegatingConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java)
at java.lang.reflect.Constructor.newInstance(Constructor.java:437)
at com.ibm.ws.managedobject.internal.ManagedObjectFactoryImpl.createManagedObject(ManagedObjectFactoryImpl.java:65)
at com.ibm.ws.websvcs.server.WSServiceInstanceFactory.createManagedObject(WSServiceInstanceFactory.java:276)
at com.ibm.ws.websvcs.server.WSServiceInstanceFactory.createServiceInstance(WSServiceInstanceFactory.java:131)
at org.apache.axis2.jaxws.server.EndpointController.handleRequest(EndpointController.java:272)
at org.apache.axis2.jaxws.server.EndpointController.invoke(EndpointController.java:103)
at org.apache.axis2.jaxws.server.JAXWSMessageReceiver.receive(JAXWSMessageReceiver.java:161)
at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:212)
at org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:172)
at com.ibm.ws.websvcs.transport.http.WASAxis2Servlet.doPost(WASAxis2Servlet.java:1633)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1235)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:779)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:478)
at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1124)
at com.ibm.ws.webcontainer.webapp.WebApp.__handleRequest(WebApp.java:4144)
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java)
at com.ibm.ws.webcontainer.webapp.WebAppImpl.handleRequest(WebAppImpl.java:2208)
at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:304)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:1030)
at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1817)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:382)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:465)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:532)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:318)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:289)
at com.ibm.ws.ssl.channel.impl.SSLConnectionLink.determineNextChannel(SSLConnectionLink.java:1084)
at com.ibm.ws.ssl.channel.impl.SSLConnectionLink$MyReadCompletedCallback.complete(SSLConnectionLink.java:658)
at com.ibm.ws.ssl.channel.impl.SSLReadServiceContext$SSLReadCompletedCallback.complete(SSLReadServiceContext.java:1820)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:175)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1892)

Answer 1

WebSphere 8.5.5 used WSJPA (build on OpenJPA) as the default JPA provider. However, starting WebSphere 9, the default JPA provider was switched to EclipseLink. If you were using EclipseLink on WebSphere 8.5.5, that means that you were providing your own EclipseLink library for WebSphere 8.5.5 since WebSphere didn't ship with EclipseLink.
When you switch to WebSphere 9, you should remove Eclipselink libraries/configuration that you had in WebSphere 8.5.5 that allowed you to use your own EclipseLink. The error you posted can result from having two EclipseLink jars visible to your application (one from your application/library and one from WebSphere).