We don't get this consistently, but we do get the following NullPointerException sometimes.

java.lang.RuntimeException: wrapped Exception: java.lang.NullPointerException
at com.icesoft.faces.webapp.http.servlet.MainServlet.service(MainServlet.java:211)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at com.icesoft.faces.webapp.xmlhttp.BlockingServlet.service(BlockingServlet.java:55)
at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:315)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:287)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:218)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:94)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:98)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:222)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1093)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:166)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1093)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:291)
at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.invokeAdapter(DefaultProcessorTask.java:670)
at com.sun.enterprise.web.connector.grizzly.comet.CometEngine.executeServlet(CometEngine.java:664)
at com.sun.enterprise.web.connector.grizzly.comet.CometEngine.handle(CometEngine.java:409)
at com.sun.enterprise.web.connector.grizzly.comet.CometAsyncFilter.doFilter(CometAsyncFilter.java:86)
at com.sun.enterprise.web.connector.grizzly.async.DefaultAsyncExecutor.invokeFilters(DefaultAsyncExecutor.java:196)
at com.sun.enterprise.web.connector.grizzly.async.DefaultAsyncExecutor.interrupt(DefaultAsyncExecutor.java:171)
at com.sun.enterprise.web.connector.grizzly.async.AsyncProcessorTask.doTask(AsyncProcessorTask.java:96)
at com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:269)
at com.sun.enterprise.web.connector.grizzly.WorkerThreadImpl.run(WorkerThreadImpl.java:122)
Caused by: java.lang.NullPointerException
at com.icesoft.faces.util.DOMUtils.compareNodes(DOMUtils.java:271)
at com.icesoft.faces.util.DOMUtils.compareNodes(DOMUtils.java:305)
at com.icesoft.faces.util.DOMUtils.compareNodes(DOMUtils.java:305)
at com.icesoft.faces.util.DOMUtils.domDiff(DOMUtils.java:255)
at com.icesoft.faces.context.PushModeSerializer.serialize(PushModeSerializer.java:69)
at com.icesoft.faces.context.BridgeFacesContext$SaveCurrentDocument.serialize(BridgeFacesContext.java:950)
at com.icesoft.faces.context.DOMResponseWriter.endDocument(DOMResponseWriter.java:190)
at com.icesoft.faces.facelets.D2DFaceletViewHandler.renderResponse(D2DFaceletViewHandler.java:284)
at com.icesoft.faces.application.D2DViewHandler.renderView(D2DViewHandler.java:158)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at com.icesoft.faces.webapp.http.core.JsfLifecycleExecutor.apply(JsfLifecycleExecutor.java:51)
at com.icesoft.faces.webapp.http.core.ReceiveSendUpdates.renderCycle(ReceiveSendUpdates.java:171)
at com.icesoft.faces.webapp.http.core.ReceiveSendUpdates.service(ReceiveSendUpdates.java:112)
at com.icesoft.faces.webapp.http.core.RequestVerifier.service(RequestVerifier.java:65)
at com.icesoft.faces.webapp.http.common.standard.PathDispatcherServer.service(PathDispatcherServer.java:55)
at com.icesoft.faces.webapp.http.servlet.BasicAdaptingServlet.service(BasicAdaptingServlet.java:48)
at com.icesoft.faces.webapp.http.servlet.PathDispatcher.service(PathDispatcher.java:55)
at com.icesoft.faces.webapp.http.servlet.SessionDispatcher.service(SessionDispatcher.java:96)
at com.icesoft.faces.webapp.http.servlet.SessionVerifier.service(SessionVerifier.java:58)
at com.icesoft.faces.webapp.http.servlet.PathDispatcher.service(PathDispatcher.java:55)
at com.icesoft.faces.webapp.http.servlet.MainServlet.service(MainServlet.java:186)
... 30 more

This typically occurs when we have a server push event sending a render call to a browser. I've googled this, and the only item I've seen this is when compressDOM is set to true in version 2.0. Our application does not have compressDOM defined in the web.xml, and we're using 1.8.2 EE P02, not version 2 of ICEfaces.