title: Liferay Portlet Taglib Cast Exception
body: <p>Here's a stacktrace I get when trying to run a portlet in Liferay Portal 6.0.6.</p>
  
  <p>Anyone has a clue what is going on?</p>
  
  <pre>
  12:40:00,146 ERROR [PortletServlet:96] javax.portlet.PortletException: javax.servlet.ServletException: javax.servlet.jsp
    .JspException: com.liferay.taglib.aui.LayoutTag cannot be cast to javax.servlet.jsp.tagext.Tag
    javax.portlet.PortletException: javax.servlet.ServletException: javax.servlet.jsp.JspException: com.liferay.taglib.aui.L
    ayoutTag cannot be cast to javax.servlet.jsp.tagext.Tag
      at com.liferay.portlet.PortletRequestDispatcherImpl.include(PortletRequestDispatcherImpl.java:110)
      at org.springframework.web.portlet.DispatcherPortlet.doRender(DispatcherPortlet.java:1137)
      at org.springframework.web.portlet.DispatcherPortlet.render(DispatcherPortlet.java:1092)
      at org.springframework.web.portlet.DispatcherPortlet.doRenderService(DispatcherPortlet.java:755)
      at org.springframework.web.portlet.FrameworkPortlet.processRequest(FrameworkPortlet.java:522)
      at org.springframework.web.portlet.FrameworkPortlet.doDispatch(FrameworkPortlet.java:470)
      at javax.portlet.GenericPortlet.render(GenericPortlet.java:233)
      at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:101)
      at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:64)
      at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:92)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
      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:646)
      at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
      at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
      at com.liferay.portlet.InvokerPortletImpl.invoke(InvokerPortletImpl.java:638)
      at com.liferay.portlet.InvokerPortletImpl.invokeRender(InvokerPortletImpl.java:723)
      at com.liferay.portlet.InvokerPortletImpl.render(InvokerPortletImpl.java:425)
      at org.apache.jsp.html.portal.render_005fportlet_jsp._jspService(render_005fportlet_jsp.java:1440)
      at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
      at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
      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:646)
      at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
      at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
      at com.liferay.portal.util.PortalImpl.renderPortlet(PortalImpl.java:3740)
      at com.liferay.portal.util.PortalUtil.renderPortlet(PortalUtil.java:1180)
      at com.liferay.portlet.layoutconfiguration.util.RuntimePortletUtil.processPortlet(RuntimePortletUtil.java:160)
      at com.liferay.portlet.layoutconfiguration.util.RuntimePortletUtil.processPortlet(RuntimePortletUtil.java:94)
      at com.liferay.portlet.layoutconfiguration.util.RuntimePortletUtil.processTemplate(RuntimePortletUtil.java:256)
      at com.liferay.portlet.layoutconfiguration.util.RuntimePortletUtil.processTemplate(RuntimePortletUtil.java:181)
      at org.apache.jsp.html.portal.layout.view.portlet_jsp._jspService(portlet_jsp.java:821)
      at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
      at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
      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:646)
      at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
      at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
      at com.liferay.portal.action.LayoutAction.includeLayoutContent(LayoutAction.java:370)
      at com.liferay.portal.action.LayoutAction.processLayout(LayoutAction.java:629)
      at com.liferay.portal.action.LayoutAction.execute(LayoutAction.java:232)
      at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
      at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
      at com.liferay.portal.struts.PortalRequestProcessor.process(PortalRequestProcessor.java:153)
      at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
      at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
      at com.liferay.portal.servlet.MainServlet.callParentService(MainServlet.java:508)
  </pre>