My environment: . Apache Tomcat/6.0.18 . JDK 1.6.0_12-b04 I got this weird message in tomcat log, too:
Nov 4, 2009 12:13:03 AM org.apache.catalina.startup.HostConfig checkResources INFO: Reloading context [/acm] Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[AppServlet] has not been started Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[jsp] has not been started Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[default] has not been started Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor processChildren SEVERE: Exception invoking periodic operation: java.lang.NoClassDefFoundError: org/apache/wicket/util/lang/PropertyResolver at org.apache.wicket.Application.internalDestroy(Application.java:887) at org.apache.wicket.protocol.http.WebApplication.internalDestroy(WebApplication.java:448) at org.apache.wicket.protocol.http.WicketFilter.destroy(WicketFilter.java:143) at org.apache.catalina.core.ApplicationFilterConfig.release(ApplicationFilterConfig.java:332) at org.apache.catalina.core.StandardContext.filterStop(StandardContext.java:3744) at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4513) at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1108) at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1214) at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:293) at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1337) at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1601) at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610) at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590) at java.lang.Thread.run(Thread.java:619) Nov 4, 2009 12:13:03 AM org.apache.catalina.core.StandardContext reload INFO: Reloading this Context has started Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[AppServlet] has not been started Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[jsp] has not been started Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[default] has not been started Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor processChildren SEVERE: Exception invoking periodic operation: java.lang.NoClassDefFoundError: org/apache/wicket/util/lang/PropertyResolver at org.apache.wicket.Application.internalDestroy(Application.java:887) at org.apache.wicket.protocol.http.WebApplication.internalDestroy(WebApplication.java:448) at org.apache.wicket.protocol.http.WicketFilter.destroy(WicketFilter.java:143) at org.apache.catalina.core.ApplicationFilterConfig.release(ApplicationFilterConfig.java:332) at org.apache.catalina.core.StandardContext.filterStop(StandardContext.java:3744) at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4513) at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3093) at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:404) at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1309) at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1601) at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610) at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610) at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590) at java.lang.Thread.run(Thread.java:619) I checked wicket jar file, and org/apache/wicket/util/lang/PropertyResolver class does exist. Is it tomcat bug? Any one has any suggestion?