struts2异常记录--java.lang.IllegalStateException

java.lang.IllegalStateException
    at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:407)
    at org.apache.struts2.dispatcher.DefaultDispatcherErrorHandler.sendErrorResponse(DefaultDispatcherErrorHandler.java:80)
    at org.apache.struts2.dispatcher.DefaultDispatcherErrorHandler.handleError(DefaultDispatcherErrorHandler.java:59)
    at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:912)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:576)
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
    at java.lang.Thread.run(Unknown Source)

错误解决：将action中的execute（）方法的返回值该为return  null   问题就解决了