tomcat启动项目，报这个错，请问是什么原因呀？

Question

2021-03-24 17:08:31 StandardContext[/ccmanager]Servlet action threw unload() exception
javax.servlet.ServletException: Servlet.destroy() for servlet action threw exception
    at org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1268)
    at org.apache.catalina.core.StandardWrapper.stop(StandardWrapper.java:1580)
    at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:952)
    at org.apache.catalina.core.StandardContext.removeChild(StandardContext.java:3148)
    at org.apache.catalina.startup.ContextConfig.stop(ContextConfig.java:676)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:218)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4513)
    at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:952)
    at org.apache.catalina.core.StandardHostDeployer.remove(StandardHostDeployer.java:670)
    at org.apache.catalina.core.StandardHost.remove(StandardHost.java:946)
    at org.apache.catalina.startup.HostConfig.undeployApps(HostConfig.java:1028)
    at org.apache.catalina.startup.HostConfig.stop(HostConfig.java:1005)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:351)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1123)
    at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1135)
    at org.apache.catalina.core.StandardEngine.stop(StandardEngine.java:483)
    at org.apache.catalina.core.StandardService.stop(StandardService.java:542)
    at org.apache.catalina.core.StandardServer.stop(StandardServer.java:2347)
    at org.apache.catalina.startup.Catalina.stop(Catalina.java:605)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:580)
    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:287)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)
----- Root Cause -----
java.lang.NullPointerException
    at com.sunyard.struts.ActionServlet.destroy(ActionServlet.java:27)
    at org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1255)
    at org.apache.catalina.core.StandardWrapper.stop(StandardWrapper.java:1580)
    at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:952)
    at org.apache.catalina.core.StandardContext.removeChild(StandardContext.java:3148)
    at org.apache.catalina.startup.ContextConfig.stop(ContextConfig.java:676)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:218)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4513)
    at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:952)
    at org.apache.catalina.core.StandardHostDeployer.remove(StandardHostDeployer.java:670)
    at org.apache.catalina.core.StandardHost.remove(StandardHost.java:946)
    at org.apache.catalina.startup.HostConfig.undeployApps(HostConfig.java:1028)
    at org.apache.catalina.startup.HostConfig.stop(HostConfig.java:1005)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:351)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1123)
    at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1135)
    at org.apache.catalina.core.StandardEngine.stop(StandardEngine.java:483)
    at org.apache.catalina.core.StandardService.stop(StandardService.java:542)
    at org.apache.catalina.core.StandardServer.stop(StandardServer.java:2347)
    at org.apache.catalina.startup.Catalina.stop(Catalina.java:605)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:580)
    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:287)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:425)

2021-03-24 17:08:31 StandardContext[/ccmanager]Shutting down log4j

Answer 1

ActionServlet类第27行打断点看一下，空指针了。

Answer 2

java.lang.NullPointerException

看看这个是什么空指针错误，关键字网上随便搜一搜，肯定有解决方法的，照着解决方案挨着操作。