大神帮忙解决一下 谢谢啦

[会飞的狼阿海]

大家好！

我的web程序在tomcat下能够正常使用，然后我将程序部署在weblogic11g上也没有出现问题。但是程序中的使用itext生成PDF时报错(在tomcat下可以正常使用)。这个问题非常郁闷，有经验的同学帮我看看。谢谢，下面是错误日志。
java.lang.NullPointerException
at weblogic.servlet.internal.ServletResponseImpl.sendContentError(ServletResponseImpl.java:611)
at weblogic.servlet.internal.ServletResponseImpl.sendError(ServletResponseImpl.java:655)
at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:770)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:505)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:96)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
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:209)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:178)