Whenever a portlet times out, the following stacktrace is recorded to the portal log file instead of a message stating that the portlet timed out:

SEVERE: Servlet.service() for servlet [portlet-context] threw exception
java.lang.NullPointerException
        at org.jasig.portal.portlet.session.PortletSessionExpirationManager.onEnd(PortletSessionExpirationManager.java:73)
        at org.apache.pluto.core.PortletServlet.notify(PortletServlet.java:287)
        at org.apache.pluto.core.PortletServlet.dispatch(PortletServlet.java:241)
        at org.apache.pluto.core.PortletServlet.doGet(PortletServlet.java:139)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:691)
        at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:594)
        at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:505)
        at org.apache.pluto.core.DefaultPortletInvokerService.invoke(DefaultPortletInvokerService.java:167)
        at org.apache.pluto.core.DefaultPortletInvokerService.render(DefaultPortletInvokerService.java:101)
        at org.apache.pluto.core.PortletContainerImpl.doRender(PortletContainerImpl.java:173)
        at org.jasig.portal.channels.portlet.SpringPortletChannelImpl.render(SpringPortletChannelImpl.java:480)
        at org.jasig.portal.channels.portlet.CSpringPortletAdaptor.renderCharacters(CSpringPortletAdaptor.java:186)
        at org.jasig.portal.ChannelRenderer$Worker.execute(ChannelRenderer.java:545)
        at org.jasig.portal.utils.threading.BaseTask.run(BaseTask.java:27)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
        at java.lang.Thread.run(Thread.java:619)