Exception while re-deploying my webapp on tomcat 6

All,

I am having problems redeploying my java webapp packaged as war using maven 3.0 (mvn package) on tomcat 6.0

However if I restart my server completely i donot get this exception and the whole app开发者_如何转开发 runs perfectly fine. Here is the details of catalina log:

WARNING: Error while removing context []
java.lang.NoClassDefFoundError: org/apache/struts2/util/ObjectFactoryDestroyable
at org.apache.struts2.dispatcher.Dispatcher.cleanup(Dispatcher.java:263)
at org.apache.struts2.dispatcher.FilterDispatcher.destroy(FilterDispatcher.java:238)
at org.apache.catalina.core.ApplicationFilterConfig.release(ApplicationFilterConfig.java:332)
at org.apache.catalina.core.StandardContext.filterStop(StandardContext.java:3731)
at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4493)
at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:924)
at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1035)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1203)
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$ContainerBackgroundProcessor.processChildren(Containe  rBase.java:1601)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.ClassNotFoundException: org.apache.struts2.util.ObjectFactoryDestroyable
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1358)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1204)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 15 more

Pls help..!