Eclipse Luna gives NullPointerException when debugging hits a breakpoint

Question

Whenever I hit a breakpoint in my code, I see an obnoxious dialog informing me that "Perspective switch job has encountered a problem", the details of which simply say "NullPointerException". The error log shows this stack trace:

java.lang.NullPointerException
    at org.eclipse.ui.internal.WorkbenchPage.showPart(WorkbenchPage.java:1298)
    at org.eclipse.ui.internal.WorkbenchPage.busyShowView(WorkbenchPage.java:1269)
    at org.eclipse.ui.internal.WorkbenchPage$13.run(WorkbenchPage.java:4144)
    at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
    at org.eclipse.ui.internal.WorkbenchPage.showView(WorkbenchPage.java:4140)
    at org.eclipse.debug.internal.ui.views.ViewContextService.showViewQuiet(ViewContextService.java:1168)
    at org.eclipse.debug.internal.ui.launchConfigurations.PerspectiveManager$4.runInUIThread(PerspectiveManager.java:528)
    at org.eclipse.debug.internal.ui.launchConfigurations.PerspectiveManager$MyUIJob$1.run(PerspectiveManager.java:229)
    at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
    at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:136)
    at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4147)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3764)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1151)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1032)
    at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:148)
    at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:636)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:579)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
    at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:135)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:382)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:236)
    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:648)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1438)

I've tried disabling perspective switching (which I don't want anyway) via Options / Run/Debug / Perspectives by setting the "Debug" perspective to "None", but it keeps getting reset to "Debug", and does not change this behavior.

This is extremely annoying, making debugging nearly unusable.

I tried adding -clean to eclipse.ini, as suggested here Myeclipse is throwing some error when i debug server ... but that had no impact, either.

Ideas?

Answer 1

I have encountered the same problem (which is likely a bug) in Eclipse Mars. Every breakpoint reached opens the error dialog you described.

I was able to prevent the error by updating the following preferences (which are also present in Luna):

1. Go to Window > Preferences
2. On the left, go to Run/Debug > Perspectives
3. In the Application Types/Launchers list, select the type of application that you are debugging.
4. On the right under Modes/Perspectives, make sure that None is selected for the Debug dropdown.

Note: I was unable to find any setting that completely disables the perspective switch for all application types, so you'll have to do this for each type you debug.