title: Error opening Debug in Preferences in Eclipse
body: <p>I got this error when I opened the Debug tab inside the Preferences in Eclipse, Does anyone know what happened?</p>
  
  <p>ps:. This happened after I did the Update.</p>
  
  <p><img src="https://i.stack.imgur.com/krm5Y.png" alt="Debug Preferences">
  EDIT:</p>
  
  <pre><code>!SUBENTRY 1 org.eclipse.equinox.registry 4 1 2012-02-12 15:21:50.290
  !MESSAGE Plug-in org.eclipse.jdt.debug.ui was unable to load class org.eclipse.jdt.debug.ui.launchConfigurations.JavaApplicationLaunchShortcut.
  !STACK 0
  org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter$TerminatingClassNotFoundException: An error occurred while automatically activating bundle org.eclipse.jdt.debug.ui (258).
      at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
      at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:462)
      at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:216)
      at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:400)
      at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:476)
      at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:429)
      at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:417)
      at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
      at java.lang.ClassLoader.loadClass(Unknown Source)
      at org.eclipse.osgi.internal.loader.BundleLoader.loadClass(BundleLoader.java:345)
      at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:229)
      at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1207)
      at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.createExecutableExtension(RegistryStrategyOSGI.java:174)
      at org.eclipse.core.internal.registry.ExtensionRegistry.createExecutableExtension(ExtensionRegistry.java:905)
      at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:243)
      at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:55)
      at org.eclipse.debug.internal.ui.launchConfigurations.LaunchShortcutExtension.getDelegate(LaunchShortcutExtension.java:410)
      at org.eclipse.debug.internal.ui.launchConfigurations.LaunchShortcutExtension.getLaunchableResource(LaunchShortcutExtension.java:516)
      at org.eclipse.debug.internal.ui.contextlaunching.LaunchingResourceManager.getLaunchableResource(LaunchingResourceManager.java:417)
      at org.eclipse.debug.internal.ui.contextlaunching.ContextRunner.selectAndLaunch(ContextRunner.java:117)
      at org.eclipse.debug.internal.ui.contextlaunching.ContextRunner.selectAndLaunch(ContextRunner.java:164)
      at org.eclipse.debug.internal.ui.contextlaunching.ContextRunner.launch(ContextRunner.java:82)
      at org.eclipse.debug.ui.actions.AbstractLaunchToolbarAction.run(AbstractLaunchToolbarAction.java:79)
      at org.eclipse.debug.ui.actions.AbstractLaunchHistoryAction.runWithEvent(AbstractLaunchHistoryAction.java:404)
      at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:241)
      at org.eclipse.ui.internal.WWinPluginAction.runWithEvent(WWinPluginAction.java:229)
      at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
      at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
      at org.eclipse.jface.action.ActionContributionItem$6.handleEvent(ActionContributionItem.java:452)
      at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
      at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
      at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4165)
      at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
      at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
      at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
      at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
      at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
      at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
      at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
      at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
      at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
      at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
      at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
      at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
      at org.eclipse.equinox.launcher.Main.main(Main.java:1386)
  Caused by: org.osgi.framework.BundleException: The activator org.eclipse.jdt.internal.debug.ui.JDIDebugUIPlugin for bundle org.eclipse.jdt.debug.ui is invalid
      at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:171)
      at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:679)
      at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:381)
      at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:299)
      at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:440)
      at org.eclipse.osgi.internal.loader.BundleLoader.setLazyTrigger(BundleLoader.java:268)
      at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
      ... 53 more
  Caused by: java.lang.NoClassDefFoundError: org/eclipse/jdt/debug/core/IJavaHotCodeReplaceListener
      at java.lang.Class.getDeclaredConstructors0(Native Method)
      at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
      at java.lang.Class.getConstructor0(Unknown Source)
      at java.lang.Class.newInstance0(Unknown Source)
      at java.lang.Class.newInstance(Unknown Source)
      at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:166)
      ... 59 more
  Caused by: java.lang.ClassNotFoundException: org.eclipse.jdt.debug.core.IJavaHotCodeReplaceListener
      at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:513)
      at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:429)
      at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:417)
      at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
      at java.lang.ClassLoader.loadClass(Unknown Source)
      ... 65 more
  </code></pre>