Juergen, You seem to be right about an incompatible API change. Are you using the snapshot build of the plugin with an older Drools runtime or vice versa? Kris jschmied wrote:

and one more ... java.lang.IllegalArgumentException: Unknown model object null at org.drools.eclipse.flow.ruleflow.editor.editpart.RuleFlowEditPartFactory.createEditPart(Unknown Source) at org.eclipse.gef.ui.parts.AbstractEditPartViewer.setContents(AbstractEditPartViewer.java:611) at org.drools.eclipse.flow.common.editor.GenericModelEditor.initializeGraphicalViewer(Unknown Source) at org.eclipse.gef.ui.parts.GraphicalEditor.createGraphicalViewer(GraphicalEditor.java:153) at org.eclipse.gef.ui.parts.GraphicalEditorWithPalette.createPartControl(GraphicalEditorWithPalette.java:62) at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:662) at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:462) at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595) at org.eclipse.ui.internal.PartPane.setVisible(PartPane.java:313) at org.eclipse.ui.internal.presentations.PresentablePart.setVisible(PresentablePart.java:180) at org.eclipse.ui.internal.presentations.util.PresentablePartFolder.select(PresentablePartFolder.java:270) at org.eclipse.ui.internal.presentations.util.LeftToRightTabOrder.select(LeftToRightTabOrder.java:65) at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation.selectPart(TabbedStackPresentation.java:473) at org.eclipse.ui.internal.PartStack.refreshPresentationSelection(PartStack.java:1256) at org.eclipse.ui.internal.PartStack.setSelection(PartStack.java:1209) at org.eclipse.ui.internal.PartStack.showPart(PartStack.java:1608) at org.eclipse.ui.internal.PartStack.add(PartStack.java:499) at org.eclipse.ui.internal.EditorStack.add(EditorStack.java:103) at org.eclipse.ui.internal.PartStack.add(PartStack.java:485) at org.eclipse.ui.internal.EditorStack.add(EditorStack.java:112) at org.eclipse.ui.internal.EditorSashContainer.addEditor(EditorSashContainer.java:63) at org.eclipse.ui.internal.EditorAreaHelper.addToLayout(EditorAreaHelper.java:225) at org.eclipse.ui.internal.EditorAreaHelper.addEditor(EditorAreaHelper.java:213) at org.eclipse.ui.internal.EditorManager.createEditorTab(EditorManager.java:778) at org.eclipse.ui.internal.EditorManager.openEditorFromDescriptor(EditorManager.java:677) at org.eclipse.ui.internal.EditorManager.openEditor(EditorManager.java:638) at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2854) at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2762) at org.eclipse.ui.internal.WorkbenchPage.access$11(WorkbenchPage.java:2754) at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2705) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2701) at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2685) at org.eclipse.ui.actions.OpenWithMenu.openEditor(OpenWithMenu.java:344) at org.eclipse.ui.actions.OpenWithMenu$2.handleEvent(OpenWithMenu.java:192) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3910) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3503) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194) 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:368) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514) at org.eclipse.equinox.launcher.Main.run(Main.java:1311) -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/problem-with-eclipse-... Sent from the Drools - Dev mailing list archive at Nabble.com.