title: JMeter - "Unexpected error" - Upgraded JMeter from 2.11 to 2.13 - Unable to open test plan
body: <p>I have upgraded JMeter from 2.11 to 2.13 and have downloaded Plugins(Standard ,Extras, Extras with lib set) for 2.13 and have moved to \lib\ext” directory.</p>
  
  <p>While trying to open a test plan i am getting below error in log :</p>
  
  <p>2016/03/16 07:10:08 ERROR - jmeter.gui.GuiPackage: Could not get GUI for kg.apc.jmeter.vizualizers.CorrectedResultCollector@3d92590b java.lang.ClassNotFoundException: kg.apc.jmeter.vizualizers.BytesThroughputOverTimeGui
      at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Class.java:264)
      at org.apache.jmeter.gui.GuiPackage.getGui(GuiPackage.java:212)
      at org.apache.jmeter.gui.tree.JMeterTreeModel.addComponent(JMeterTreeModel.java:153)
      at org.apache.jmeter.gui.tree.JMeterTreeModel.addSubTree(JMeterTreeModel.java:129)
      at org.apache.jmeter.gui.tree.JMeterTreeModel.addSubTree(JMeterTreeModel.java:121)
      at org.apache.jmeter.gui.GuiPackage.addSubTree(GuiPackage.java:495)
      at org.apache.jmeter.gui.action.Load.insertLoadedTree(Load.java:193)
      at org.apache.jmeter.gui.action.Load.loadProjectFile(Load.java:131)
      at org.apache.jmeter.gui.action.Load.loadProjectFile(Load.java:102)
      at org.apache.jmeter.gui.action.Load.doAction(Load.java:89)
      at org.apache.jmeter.gui.action.ActionRouter.performAction(ActionRouter.java:81)
      at org.apache.jmeter.gui.action.ActionRouter.access$000(ActionRouter.java:40)
      at org.apache.jmeter.gui.action.ActionRouter$1.run(ActionRouter.java:63)
      at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
      at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
      at java.awt.EventQueue.access$500(EventQueue.java:97)
      at java.awt.EventQueue$3.run(EventQueue.java:709)
      at java.awt.EventQueue$3.run(EventQueue.java:703)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
      at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
      at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
      at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
      at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
      at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)</p>
  
  <p>2016/03/16 07:10:08 WARN  - jmeter.gui.action.Load: Unexpected error java.lang.NullPointerException
      at org.apache.jmeter.gui.tree.JMeterTreeModel.addComponent(JMeterTreeModel.java:154)
      at org.apache.jmeter.gui.tree.JMeterTreeModel.addSubTree(JMeterTreeModel.java:129)
      at org.apache.jmeter.gui.tree.JMeterTreeModel.addSubTree(JMeterTreeModel.java:121)
      at org.apache.jmeter.gui.GuiPackage.addSubTree(GuiPackage.java:495)
      at org.apache.jmeter.gui.action.Load.insertLoadedTree(Load.java:193)
      at org.apache.jmeter.gui.action.Load.loadProjectFile(Load.java:131)
      at org.apache.jmeter.gui.action.Load.loadProjectFile(Load.java:102)
      at org.apache.jmeter.gui.action.Load.doAction(Load.java:89)
      at org.apache.jmeter.gui.action.ActionRouter.performAction(ActionRouter.java:81)
      at org.apache.jmeter.gui.action.ActionRouter.access$000(ActionRouter.java:40)
      at org.apache.jmeter.gui.action.ActionRouter$1.run(ActionRouter.java:63)
      at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
      at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
      at java.awt.EventQueue.access$500(EventQueue.java:97)
      at java.awt.EventQueue$3.run(EventQueue.java:709)
      at java.awt.EventQueue$3.run(EventQueue.java:703)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
      at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
      at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
      at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
      at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
      at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)</p>