jsp status500错误(我之前调试都是好的,什么都没改现在却报500错误 )
jsp   status500错误(我之前调试都是好的,什么都没改现在却报500错误   )
我之前两个用到javabean的页面调试都正常，什么都没改动,不知道为什么现在报500错误了

type   Exception   report

message  

description   The   server   encountered   an   internal   error   ()   that   prevented   it   from   fulfilling   this   request.

exception  

org.apache.jasper.JasperException
at   org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:254)
at   org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
at   org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at   javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at   org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at   org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at   org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at   org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at   org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at   org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at   org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at   org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at   org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at   org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at   org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2416)
at   org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at   org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at   org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at   org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at   org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at   org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at   org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at   org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at   org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at   org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at   org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at   org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at   org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
at   org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:601)
at   org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
at   org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
at   org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)


请问这是为什么呀?
我是新学，所以请大家多帮帮忙

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