NullPointer RenderResponse.execute JSF2.1.7

问题

We have JSF2.1.7 in weblogic10.3.4 ,we get the following at some times , what could be the root cause

java.lang.NullPointerException
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:96)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)
    at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at com.ads.retail.application.ecs.filter.ECSDisableDynamicClientCache.doFilter(ECSDisableDynamicClientCache.java:34)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at com.ads.retail.application.ecs.filter.SiteRedirectFilter.doFilter(SiteRedirectFilter.java:139)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at com.ads.retail.application.ecs.filter.StaticContentFilter.doFilter(StaticContentFilter.java:35)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3715)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3681)
    at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
    at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)
    at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2277)
    at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2183)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1454)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:207)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:176)

来源：https://stackoverflow.com/questions/10249134/nullpointer-renderresponse-execute-jsf2-1-7