java.lang.IllegalStateException: The data object MultiFileObject@4243a[Templates/Project/Samples/Standard] is invalid; you may not call getNodeDelegate on it any more; see #17020 and please fix your code
        at org.openide.loaders.DataObject.getNodeDelegate(DataObject.java:267)
        at org.netbeans.modules.project.ui.TemplatesPanel$CategoriesChildren.createNodes(TemplatesPanel.java:220)
        at org.netbeans.modules.project.ui.TemplatesPanel$CategoriesChildren.createNodes(TemplatesPanel.java:192)
        at org.openide.nodes.Children$Keys$KE.nodes(Children.java:1474)
        at org.openide.nodes.ChildrenArray.nodesFor(ChildrenArray.java:168)
        at org.openide.nodes.EntrySupport$Default$Info.nodes(EntrySupport.java:924)
        at org.openide.nodes.EntrySupport$Default.updateAdd(EntrySupport.java:491)
        at org.openide.nodes.EntrySupport$Default.setEntries(EntrySupport.java:324)
        at org.openide.nodes.Children$Keys$2.run(Children.java:1368)
        at org.openide.util.Mutex.leaveImpl(Mutex.java:902)
        at org.openide.util.Mutex.leave(Mutex.java:835)
        at org.openide.util.Mutex.readAccess(Mutex.java:364)
        at org.openide.explorer.view.VisualizerNode$QP.run(VisualizerNode.java:660)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:180)
        at java.awt.Dialog$1.run(Dialog.java:535)
        at java.awt.Dialog$2.run(Dialog.java:563)
        at java.security.AccessController.doPrivileged(AccessController.java:0)
        at java.awt.Dialog.show(Dialog.java:561)
        at javax.swing.JFileChooser.showDialog(JFileChooser.java:728)
        at javax.swing.JFileChooser.showOpenDialog(JFileChooser.java:620)
        at org.netbeans.modules.project.ui.actions.OpenProject.actionPerformed(OpenProject.java:101)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1882)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2202)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:232)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
        at java.awt.Component.processMouseEvent(Component.java:5602)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3135)
        at java.awt.Component.processEvent(Component.java:5367)
        at java.awt.Container.processEvent(Container.java:2010)
        at java.awt.Component.dispatchEventImpl(Component.java:4068)
        at java.awt.Container.dispatchEventImpl(Container.java:2068)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4256)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:3936)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:3866)
        at java.awt.Container.dispatchEventImpl(Container.java:2054)
        at java.awt.Window.dispatchEventImpl(Window.java:1791)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)