Drew a model, saved it, modeller won't open it back again. .bpmn with "Unhandled exception during import" diagnostics. Stack trace:

org.camunda.bpm.modeler.core.importer.ImportException: Unhandled exception during import
at org.camunda.bpm.modeler.core.importer.ModelImportCommand.doExecute(ModelImportCommand.java:54)
at org.eclipse.emf.transaction.RecordingCommand.execute(RecordingCommand.java:135)
at org.eclipse.graphiti.ui.internal.editor.GFWorkspaceCommandStackImpl.execute(GFWorkspaceCommandStackImpl.java:115)
at org.eclipse.emf.transaction.impl.AbstractTransactionalCommandStack.execute(AbstractTransactionalCommandStack.java:219)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2RefreshBehavior.importDiagram(Bpmn2RefreshBehavior.java:97)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2RefreshBehavior.access$0(Bpmn2RefreshBehavior.java:89)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2RefreshBehavior$1.doExecute(Bpmn2RefreshBehavior.java:74)
at org.eclipse.emf.transaction.RecordingCommand.execute(RecordingCommand.java:135)
at org.eclipse.emf.workspace.EMFCommandOperation.doExecute(EMFCommandOperation.java:119)
at org.eclipse.emf.workspace.AbstractEMFOperation.execute(AbstractEMFOperation.java:150)
at org.eclipse.core.commands.operations.DefaultOperationHistory.execute(DefaultOperationHistory.java:513)
at org.eclipse.emf.workspace.impl.WorkspaceCommandStackImpl.doExecute(WorkspaceCommandStackImpl.java:208)
at org.eclipse.emf.transaction.impl.AbstractTransactionalCommandStack.execute(AbstractTransactionalCommandStack.java:165)
at org.eclipse.graphiti.ui.internal.editor.GFWorkspaceCommandStackImpl.execute(GFWorkspaceCommandStackImpl.java:84)
at org.eclipse.emf.transaction.impl.AbstractTransactionalCommandStack.execute(AbstractTransactionalCommandStack.java:219)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2RefreshBehavior.importBpmnDiagram(Bpmn2RefreshBehavior.java:70)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2RefreshBehavior.autoUpdate(Bpmn2RefreshBehavior.java:47)
at org.eclipse.graphiti.ui.editor.DefaultRefreshBehavior.handleAutoUpdateAtStartup(DefaultRefreshBehavior.java:101)
at org.eclipse.graphiti.ui.editor.DiagramBehavior.setInput(DiagramBehavior.java:394)
at org.eclipse.graphiti.ui.editor.DiagramEditor.setInput(DiagramEditor.java:306)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2Editor.setInput(Bpmn2Editor.java:284)
at org.eclipse.graphiti.ui.editor.DiagramEditor.init(DiagramEditor.java:223)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2Editor.init(Bpmn2Editor.java:158)
at org.eclipse.ui.part.MultiPageEditorPart.addPage(MultiPageEditorPart.java:239)
at org.eclipse.ui.part.MultiPageEditorPart.addPage(MultiPageEditorPart.java:213)
at org.camunda.bpm.modeler.ui.diagram.editor.Bpmn2MultiPageEditor.createPages(Bpmn2MultiPageEditor.java:82)
at org.eclipse.ui.part.MultiPageEditorPart.createPartControl(MultiPageEditorPart.java:362)
at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.createPartControl(CompatibilityPart.java:141)
at org.eclipse.ui.internal.e4.compatibility.CompatibilityEditor.createPartControl(CompatibilityEditor.java:99)
at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.create(CompatibilityPart.java:327)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:55)
at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:888)
at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:869)
at org.eclipse.e4.core.internal.di.InjectorImpl.inject(InjectorImpl.java:120)
at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:337)
at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:258)
at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:162)
at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.createFromBundle(ReflectionContributionFactory.java:104)
at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.doCreate(ReflectionContributionFactory.java:73)
at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.create(ReflectionContributionFactory.java:55)
at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer.createWidget(ContributedPartRenderer.java:127)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createWidget(PartRenderingEngine.java:983)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:662)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$2(PartRenderingEngine.java:737)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$7.run(PartRenderingEngine.java:731)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.showTab(StackRenderer.java:1246)
at org.eclipse.e4.ui.workbench.renderers.swt.LazyStackRenderer$1.handleEvent(LazyStackRenderer.java:69)
at org.eclipse.e4.ui.services.internal.events.UIEventHandler$1.run(UIEventHandler.java:40)
at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:187)
at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:156)
at org.eclipse.swt.widgets.Display.syncExec(Display.java:4590)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application$1.syncExec(E4Application.java:218)
at org.eclipse.e4.ui.services.internal.events.UIEventHandler.handleEvent(UIEventHandler.java:36)
at org.eclipse.equinox.internal.event.EventHandlerWrapper.handleEvent(EventHandlerWrapper.java:197)
at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:197)
at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:1)
at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
at org.eclipse.equinox.internal.event.EventAdminImpl.dispatchEvent(EventAdminImpl.java:135)
at org.eclipse.equinox.internal.event.EventAdminImpl.sendEvent(EventAdminImpl.java:78)
at org.eclipse.equinox.internal.event.EventComponent.sendEvent(EventComponent.java:39)
at org.eclipse.e4.ui.services.internal.events.EventBroker.send(EventBroker.java:81)
at org.eclipse.e4.ui.internal.workbench.UIEventPublisher.notifyChanged(UIEventPublisher.java:59)
at org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify(BasicNotifierImpl.java:374)
at org.eclipse.e4.ui.model.application.ui.impl.ElementContainerImpl.setSelectedElement(ElementContainerImpl.java:171)
at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.showElementInWindow(ModelServiceImpl.java:488)
at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.bringToTop(ModelServiceImpl.java:454)
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.delegateBringToTop(PartServiceImpl.java:705)
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.bringToTop(PartServiceImpl.java:392)
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.showPart(PartServiceImpl.java:1145)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:3210)
at org.eclipse.ui.internal.WorkbenchPage.access$23(WorkbenchPage.java:3125)
at org.eclipse.ui.internal.WorkbenchPage$9.run(WorkbenchPage.java:3107)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3102)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3066)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3056)
at org.eclipse.ui.ide.IDE.openEditor(IDE.java:541)
at org.eclipse.ui.ide.IDE.openEditor(IDE.java:500)
at org.eclipse.jdt.internal.ui.javaeditor.EditorUtility.openInEditor(EditorUtility.java:360)
at org.eclipse.jdt.internal.ui.javaeditor.EditorUtility.openInEditor(EditorUtility.java:167)
at org.eclipse.jdt.ui.actions.OpenAction.run(OpenAction.java:268)
at org.eclipse.jdt.ui.actions.OpenAction.run(OpenAction.java:233)
at org.eclipse.jdt.ui.actions.SelectionDispatchAction.dispatchRun(SelectionDispatchAction.java:275)
at org.eclipse.jdt.ui.actions.SelectionDispatchAction.run(SelectionDispatchAction.java:251)
at org.eclipse.jdt.internal.ui.navigator.OpenAndExpand.run(OpenAndExpand.java:50)
at org.eclipse.ui.actions.RetargetAction.run(RetargetAction.java:229)
at org.eclipse.ui.navigator.CommonNavigatorManager$3.open(CommonNavigatorManager.java:185)
at org.eclipse.ui.OpenAndLinkWithEditorHelper$InternalListener.open(OpenAndLinkWithEditorHelper.java:48)
at org.eclipse.jface.viewers.StructuredViewer$2.run(StructuredViewer.java:853)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:50)
at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:178)
at org.eclipse.jface.viewers.StructuredViewer.fireOpen(StructuredViewer.java:850)
at org.eclipse.jface.viewers.StructuredViewer.handleOpen(StructuredViewer.java:1142)
at org.eclipse.ui.navigator.CommonViewer.handleOpen(CommonViewer.java:462)
at org.eclipse.jface.viewers.StructuredViewer$6.handleOpen(StructuredViewer.java:1249)
at org.eclipse.jface.util.OpenStrategy.fireOpenEvent(OpenStrategy.java:278)
at org.eclipse.jface.util.OpenStrategy.access$2(OpenStrategy.java:272)
at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:313)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4454)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1388)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3799)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3409)
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:380)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
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)
Caused by: java.lang.NullPointerException
at org.camunda.bpm.modeler.core.layout.util.ConversionUtil.point(ConversionUtil.java:86)
at org.camunda.bpm.modeler.core.importer.handlers.AbstractEdgeHandler.positionsMatch(AbstractEdgeHandler.java:241)
at org.camunda.bpm.modeler.core.importer.handlers.AbstractEdgeHandler.getReferencedChopboxAnchor(AbstractEdgeHandler.java:220)
at org.camunda.bpm.modeler.core.importer.handlers.AbstractEdgeHandler.createAnchorOnContainer(AbstractEdgeHandler.java:188)
at org.camunda.bpm.modeler.core.importer.handlers.AbstractEdgeHandler.createTargetAnchor(AbstractEdgeHandler.java:149)
at org.camunda.bpm.modeler.core.importer.handlers.AbstractEdgeHandler.createConnectionAndSetBendpoints(AbstractEdgeHandler.java:103)
at org.camunda.bpm.modeler.core.importer.handlers.SequenceFlowHandler.handleEdge(SequenceFlowHandler.java:69)
at org.camunda.bpm.modeler.core.importer.handlers.SequenceFlowHandler.handleEdge(SequenceFlowHandler.java:1)
at org.camunda.bpm.modeler.core.importer.handlers.AbstractEdgeHandler.handleDiagramElement(AbstractEdgeHandler.java:70)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleDiagramElement(ModelImport.java:820)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleSequenceFlow(ModelImport.java:792)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleSequenceFlows(ModelImport.java:501)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleExpandedParticipant(ModelImport.java:462)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleParticipant(ModelImport.java:431)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleCollaboration(ModelImport.java:401)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleDefinitions(ModelImport.java:251)
at org.camunda.bpm.modeler.core.importer.ModelImport.handleDocumentRoot(ModelImport.java:189)
at org.camunda.bpm.modeler.core.importer.ModelImport.execute(ModelImport.java:170)
at org.camunda.bpm.modeler.core.importer.ModelImportCommand.doExecute(ModelImportCommand.java:50)
... 133 more

.bpmn model available upon request.

Thank you!
WBR,
Andrii