com.sun.jdi.VMDisconnectedException: connection is closed
        at com.sun.tools.jdi.TargetVM.send(TargetVM.java:274)
        at com.sun.tools.jdi.VirtualMachineImpl.sendToTarget(VirtualMachineImpl.java:1011)
        at com.sun.tools.jdi.PacketStream.send(PacketStream.java:41)
        at com.sun.tools.jdi.JDWP$ThreadReference$FrameCount.enqueueCommand(JDWP.java:5300)
        at com.sun.tools.jdi.JDWP$ThreadReference$FrameCount.process(JDWP.java:5286)
        at com.sun.tools.jdi.ThreadReferenceImpl.frameCount(ThreadReferenceImpl.java:254)
        at org.netbeans.modules.debugger.jpda.models.JPDAThreadImpl.getStackDepth(JPDAThreadImpl.java:482)
        at org.netbeans.modules.debugger.jpda.ui.models.DebuggingNodeModel.getDisplayName(DebuggingNodeModel.java:212)
        at org.netbeans.modules.debugger.jpda.ui.models.DebuggingNodeModel.getDisplayName(DebuggingNodeModel.java:174)
        at org.netbeans.spi.viewmodel.Models$DelegatingNodeModel.getDisplayName(Models.java:1859)
        at org.netbeans.modules.debugger.jpda.ui.models.DebuggingMonitorModel.getDisplayName(DebuggingMonitorModel.java:331)
        at org.netbeans.spi.viewmodel.Models$CompoundNodeModel.getDisplayName(Models.java:803)
        at org.netbeans.spi.viewmodel.Models$CompoundModel.getDisplayName(Models.java:3009)
        at org.netbeans.modules.viewmodel.TreeModelNode.refresh(TreeModelNode.java:325)
        at org.netbeans.modules.viewmodel.TreeModelRoot$1.run(TreeModelRoot.java:144)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:284)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)