500 Servlet Exception

java.lang.NoClassDefFoundError: org/apache/xerces/dom/DeferredDocumentImpl
	at com.expressdx.web.xml.BasicXMLReaderBean.getXMLFile(BasicXMLReaderBean.java:108)
	at com.expressdx.web.xml.BasicXMLReaderBean.getDOMFile(BasicXMLReaderBean.java:82)
	at com.expressdx.web.xml.OnionRSSFeedReaderBean.parseRSSFeed(OnionRSSFeedReaderBean.java:52)
	at com.expressdx.web.xml.OnionRSSFeedReaderBean.getReaderDisplay(OnionRSSFeedReaderBean.java:92)
	at _onionFeed__jsp._jspService(/onionFeed.jsp:19)
	at com.caucho.jsp.JavaPage.service(JavaPage.java:75)
	at com.caucho.jsp.Page.subservice(Page.java:506)
	at com.caucho.server.http.FilterChainPage.doFilter(FilterChainPage.java:182)
	at com.caucho.server.http.Invocation.service(Invocation.java:315)
	at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
	at com.caucho.server.http.QRequestDispatcher.include(QRequestDispatcher.java:364)
	at com.caucho.server.http.QRequestDispatcher.include(QRequestDispatcher.java:275)
	at com.caucho.jsp.QPageContext.include(QPageContext.java:550)
	at _index__jsp._jspService(_index__jsp.java:26)
	at com.caucho.jsp.JavaPage.service(JavaPage.java:75)
	at com.caucho.jsp.Page.subservice(Page.java:506)
	at com.caucho.server.http.FilterChainPage.doFilter(FilterChainPage.java:182)
	at com.caucho.server.http.Invocation.service(Invocation.java:315)
	at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
	at com.caucho.server.http.RunnerRequest.handleRequest(RunnerRequest.java:346)
	at com.caucho.server.http.RunnerRequest.handleConnection(RunnerRequest.java:274)
	at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
	at java.lang.Thread.run(Thread.java:534)