title: Java Web Application Error - Can't understand why it's happening now
body: <p>I am using eclipse and I can build the webapp and deploy it to Jboss4.2.1. It was working previously and I haven't changed anything really extensively to make this error come about. When I go to the webapp thru my browser, I previously have been signing in with a generic username and then I could use my webapp as usual. </p>
  
  <p>Now when I go to the webapp thru the browser, this error occurs repeatedly and will not show anything. Here is the error that I am receiving:</p>
  
  <pre><code>07:55:06,174 INFO  [security] User '' attempting login via SiteMinder...
  07:55:06,174 INFO  [security] User '' attempting login via SiteMinder...
  07:55:06,174 ERROR [[jsp]] Servlet.service() for servlet jsp threw exception
  java.lang.LinkageError: Class javax/el/ExpressionFactory violates loader constraints
      at org.apache.jsp.WEB_002dINF.jsp.layout.header_jsp._jspx_meth_c_005fset_005f0(header_jsp.java:207)
      at org.apache.jsp.WEB_002dINF.jsp.layout.header_jsp._jspx_meth_c_005fif_005f0(header_jsp.java:179)
      at org.apache.jsp.WEB_002dINF.jsp.layout.header_jsp._jspService(header_jsp.java:82)
      at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:387)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:687)
      at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:590)
      at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:505)
      at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
      at org.apache.jasper.runtime.PageContextImpl.doInclude(PageContextImpl.java:643)
      at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:637)
      at net.sourceforge.stripes.tag.layout.LayoutRenderTag.doEndTag(LayoutRenderTag.java:122)
      at org.apache.jsp.WEB_002dINF.jsp.layout.layout_jsp._jspx_meth_stripes_005flayout_002drender_005f0(layout_jsp.java:796)
      at org.apache.jsp.WEB_002dINF.jsp.layout.layout_jsp._jspx_meth_stripes_005flayout_002dcomponent_005f2(layout_jsp.java:759)
      at org.apache.jsp.WEB_002dINF.jsp.layout.layout_jsp._jspService(layout_jsp.java:200)
      at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:387)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:687)
      at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:590)
      at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:505)
      at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
      at org.apache.jasper.runtime.PageContextImpl.doInclude(PageContextImpl.java:643)
      at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:637)
      at net.sourceforge.stripes.tag.layout.LayoutRenderTag.doEndTag(LayoutRenderTag.java:122)
      at org.apache.jsp.view.public_.login_jsp._jspService(login_jsp.java:335)
      at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:387)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at net.sourceforge.stripes.controller.StripesFilter.doFilter(StripesFilter.java:180)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:112)
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:265)
      at org.acegisecurity.ui.switchuser.SwitchUserProcessingFilter.doFilter(SwitchUserProcessingFilter.java:341)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:107)
      at org.acegisecurity.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:72)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:110)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:110)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.wrapper.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:81)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:229)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:229)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:286)
      at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
      at org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:149)
      at org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:98)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
      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:230)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
      at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
      at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
      at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:241)
      at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
      at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:580)
      at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
      at java.lang.Thread.run(Thread.java:595)
  </code></pre>
  
  <p>Any help would be greatly appreciated. </p>