LogManager.resetConfiguration() does not drop the JMX MBeans created by HierarchyDynamicMBean. When executed twice, the following MBeanServer mbs = ...; Properties props = ...; HierarchyDynamicMBean hdm = new HierarchyDynamicMBean(); mbs.registerMBean(hdm, new ObjectName("log4j:hiearchy=default")); Enumeration<Logger> iter = (Enumeration<Logger>) LogManager.getLoggerRepository().getCurrentLoggers(); while (iter.hasMoreElements()) { hdm.addLoggerMBean(iter .nextElement() .getName()); } LogManager.resetConfiguration(); PropertyConfigurator.configure(props); throws org.apache.log4j.jmx.LoggerDynamicMBean <ERROR > Could not add appenderMBean for [F]. javax.management.InstanceAlreadyExistsException: log4j:appender=F at com.sun.jmx.mbeanserver.RepositorySupport.addMBean(RepositorySupport.java:452) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.internal_addObject(DefaultMBeanServerInterceptor.java:1410) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:936) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:337) at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:497) at org.apache.log4j.jmx.LoggerDynamicMBean.registerAppenderMBean(Unknown Source) at org.apache.log4j.jmx.LoggerDynamicMBean.handleNotification(Unknown Source) at javax.management.NotificationBroadcasterSupport.handleNotification(NotificationBroadcasterSupport.java:221) at javax.management.NotificationBroadcasterSupport.sendNotification(NotificationBroadcasterSupport.java:184) at org.apache.log4j.jmx.HierarchyDynamicMBean.addAppenderEvent(Unknown Source) at org.apache.log4j.Hierarchy.fireAddAppenderEvent(Hierarchy.java:192) at org.apache.log4j.Category.addAppender(Category.java:162) at org.apache.log4j.PropertyConfigurator.parseCategory(PropertyConfigurator.java:614) at org.apache.log4j.PropertyConfigurator.configureRootCategory(PropertyConfigurator.java:509) at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:415) at org.apache.log4j.PropertyConfigurator.configure(PropertyConfigurator.java:349) ...