Eclipse Jee Oxygen error when debugging Eclipse Applications - eclipse

Question

This is about Eclipse Jee Oxygen (eclipse.buildId = 4.7.3.M20180301-0715).
Until this morning everything was running fine, then Eclipse update poped-up.
I decided to take the update and after restarting Eclipse I tried to debug a plugin project I'm working on. When I clicked Debug as > Eclipse Application menu, the other Eclipse instance started to be loaded, but it was interrupted with the following error stack:
java.lang.NullPointerException
at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.<init>(ModelServiceImpl.java:122)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultContext(E4Application.java:511)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:204)
at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:614)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:594)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:151)
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:388)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:653)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:590)
at org.eclipse.equinox.launcher.Main.run(Main.java:1499)
at org.eclipse.equinox.launcher.Main.main(Main.java:1472)
I tryed to revert the update but now nothing works anymore. This is real only for debugging an Eclipse Application, other features of Eclipse seem to be ok.
Any ideas?

Answer 1

Go to your Target Platform preference page and make sure its settings are still valid by resetting to the defaults if needed.

Answer 2

After many unsuccessful attempts to fix the problem, I decided to create a new workspace and check out my project from Subversion, then I updated some files that were not yet committed and everything got back to work again.
I don't consider this a really good solution since what I did was to dodge the issue, but at least it shows that the problem is not in Eclipse itself, but in some workspace condition.