netbeans莫明其妙的报错

netbeans里莫名奇妙的报错：Illegal access: this web application instance has been stopped already.  Could not load java.lang.Object。

经过多次试验后，发现，在项目里新增了一个log4j.properties文件，直接运行项目就报这个错。如果停了tomcat后再运行项目，就没有问题了，netbeans真是奇怪。

信息: Illegal access: this web application instance has been stopped already.  Could not load java.lang.Object.  The eventual following stack trace is caused by an error thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access, and has no functional impact.

java.lang.IllegalStateException

        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1246)

        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1206)

        at com.sun.faces.application.ConverterPropertyEditorFactory$DisposableClassLoader.loadClass(ConverterPropertyEditorFactory.java:447)

        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)

        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)

        at java.lang.Class.getDeclaredConstructors0(Native Method)

        at java.lang.Class.privateGetDeclaredConstructors(Class.java:2389)

        at java.lang.Class.getConstructor0(Class.java:2699)

        at java.lang.Class.newInstance0(Class.java:326)

        at java.lang.Class.newInstance(Class.java:308)

        at java.beans.PropertyEditorManager.findEditor(PropertyEditorManager.java:79)

        at com.sun.faces.application.ApplicationImpl.addPropertyEditorIfNecessary(ApplicationImpl.java:690)

        at com.sun.faces.application.ApplicationImpl.addConverter(ApplicationImpl.java:660)

        at com.sun.faces.config.ConfigureListener.configure(ConfigureListener.java:727)

        at com.sun.faces.config.ConfigureListener.configure(ConfigureListener.java:489)

        at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:381)

        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3843)

        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4350)

        at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3099)

        at org.apache.catalina.manager.ManagerServlet.reload(ManagerServlet.java:913)

        at org.apache.catalina.manager.ManagerServlet.doGet(ManagerServlet.java:359)

        at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)

        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

        at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:196)

        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:175)

        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525)

        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:844)

        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)