Problem in shifting from tomcat 5 to 6

Intially for my project i had configured tomcat 5.5 and it was moving smoothly for months. Recently i had configured my fedora 6 to have two tomcat (5.5 & 6). Every thing working fine. But my project which is working only in tomcat 5.5 but not in tomcat 6. I checked the libs of both but i cant figured it out. The docbase is working in tomcat 5.5 but not working in tomcat 6.
I am getting excepption while startting tomcat 6 itself such as

Apr 3, 2009 11:13:52 AM org.apache.commons.digester.Digester getParser
SEVERE: Digester.getParser: 
org.xml.sax.SAXNotRecognizedException: Feature: http://apache.org/xml/features/validation/dynamic
        at org.apache.crimson.parser.XMLReaderImpl.setFeature(XMLReaderImpl.java:204)
        at org.apache.crimson.jaxp.SAXParserImpl.setFeatures(SAXParserImpl.java:137)
        at org.apache.crimson.jaxp.SAXParserFactoryImpl.newSAXParser0(SAXParserFactoryImpl.java:101)
        at org.apache.crimson.jaxp.SAXParserFactoryImpl.setFeature(SAXParserFactoryImpl.java:140)
        at org.apache.commons.digester.parser.XercesParser.configureXerces(XercesParser.java:185)
        at org.apache.commons.digester.parser.XercesParser.newSAXParser(XercesParser.java:138)
        at org.apache.commons.digester.ParserFeatureSetterFactory.newSAXParser(ParserFeatureSetterFactory.java:71)
        at org.apache.commons.digester.Digester.getParser(Digester.java:692)
        at org.apache.commons.digester.Digester.getXMLReader(Digester.java:899)
        at org.apache.commons.digester.Digester.parse(Digester.java:1647)
        at org.apache.struts.action.ActionServlet.parseModuleConfigFile(ActionServlet.java:708)
        at org.apache.struts.action.ActionServlet.initModuleConfig(ActionServlet.java:670)
        at org.apache.struts.action.ActionServlet.init(ActionServlet.java:329)
        at javax.servlet.GenericServlet.init(GenericServlet.java:212)
        at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172)
        at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992)
        at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525)
        at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:627)
        at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:553)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:488)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
        at org.apache.catalina.core.StandardService.start(StandardService.java:516)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Apr 3, 2009 11:13:52 AM org.apache.catalina.core.ApplicationContext log
SEVERE: StandardWrapper.Throwable
java.lang.NullPointerException
        at org.apache.commons.digester.Digester.getXMLReader(Digester.java:899)
        at org.apache.commons.digester.Digester.parse(Digester.java:1647)
        at org.apache.struts.action.ActionServlet.parseModuleConfigFile(ActionServlet.java:708)
        at org.apache.struts.action.ActionServlet.initModuleConfig(ActionServlet.java:670)
        at org.apache.struts.action.ActionServlet.init(ActionServlet.java:329)
        at javax.servlet.GenericServlet.init(GenericServlet.java:212)
        at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172)
        at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992)
        at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525)
        at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:627)
        at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:553)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:488)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
        at org.apache.catalina.core.StandardService.start(StandardService.java:516)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Apr 3, 2009 11:13:52 AM org.apache.catalina.core.StandardContext loadOnStartup
SEVERE: Servlet /XXXXXStage threw load() exception
java.lang.NullPointerException
        at org.apache.commons.digester.Digester.getXMLReader(Digester.java:899)
        at org.apache.commons.digester.Digester.parse(Digester.java:1647)
        at org.apache.struts.action.ActionServlet.parseModuleConfigFile(ActionServlet.java:708)
        at org.apache.struts.action.ActionServlet.initModuleConfig(ActionServlet.java:670)
        at org.apache.struts.action.ActionServlet.init(ActionServlet.java:329)
        at javax.servlet.GenericServlet.init(GenericServlet.java:212)
        at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172)
        at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992)
        at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525)
        at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:627)
        at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:553)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:488)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
        at org.apache.catalina.core.StandardService.start(StandardService.java:516)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
Apr 3, 2009 11:13:53 AM org.apache.catalina.core.ApplicationContext log
INFO: ContextListener: contextInitialized()
Apr 3, 2009 11:13:53 AM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener: contextInitialized()
Apr 3, 2009 11:13:53 AM org.apache.coyote.http11.Http11Protocol start
INFO: Starting Coyote HTTP/1.1 on http-1.1.51.66-8081
Apr 3, 2009 11:13:53 AM org.apache.catalina.connector.MapperListener registerEngine
WARNING: Unknown default host: localhost
[GC [DefNew: 16739K->1595K(18176K), 0.0129290 secs] 18145K->3001K(260160K), 0.0129970 secs] [Times: user=0.01 sys=0.00, real=0.02 secs] 
Apr 3, 2009 11:13:53 AM org.apache.jk.common.ChannelSocket init
INFO: JK: ajp13 listening on /0.0.0.0:8010
Apr 3, 2009 11:13:53 AM org.apache.jk.server.JkMain start
INFO: Jk running ID=0 time=0/59  config=null
Apr 3, 2009 11:13:53 AM org.apache.catalina.connector.MapperListener registerEngine
WARNING: Unknown default host: localhost
Apr 3, 2009 11:13:53 AM org.apache.catalina.startup.Catalina start
INFO: Server startup in 3562 ms

When i run from browser the filters i configured was running but something is going wrong after that and exception is thrown

org.apache.jasper.JasperException: java.lang.NullPointerException: Module 'null' not found.
        at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
        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 com.XXXXX.YYYY.Filter.RequestLog.doFilter(RequestLog.java:51)
        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(Thread.java:619)
Caused by: java.lang.NullPointerException: Module 'null' not found.
        at org.apache.struts.taglib.TagUtils.getModuleConfig(TagUtils.java:743)
        at org.apache.struts.taglib.TagUtils.computeURLWithCharEncoding(TagUtils.java:360)
        at org.apache.struts.taglib.html.RewriteTag.doStartTag(RewriteTag.java:54)
        at org.apache.jsp.jsp.index_jsp._jspx_meth_html_005frewrite_005f0(index_jsp.java:363)
        at org.apache.jsp.jsp.index_jsp._jspService(index_jsp.java:97)
        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:374)
        ... 18 more

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