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:934)
        at com.sun.tools.jdi.PacketStream.send(PacketStream.java:41)
        at com.sun.tools.jdi.JDWP$ObjectReference$EnableCollection.enqueueCommand(JDWP.java:4439)
        at com.sun.tools.jdi.JDWP$ObjectReference$EnableCollection.process(JDWP.java:4425)
        at com.sun.tools.jdi.ObjectReferenceImpl.enableCollection(ObjectReferenceImpl.java:416)
        at org.netbeans.modules.debugger.jpda.expr.EvaluationContext.enableCollectionOfObjects(EvaluationContext.java:310)
        at org.netbeans.modules.debugger.jpda.expr.EvaluationContext$1.propertyChange(EvaluationContext.java:286)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:333)
        at org.netbeans.modules.debugger.jpda.JPDADebuggerImpl.firePropertyChange(JPDADebuggerImpl.java:1837)
        at org.netbeans.modules.debugger.jpda.JPDADebuggerImpl.setState(JPDADebuggerImpl.java:1821)
        at org.netbeans.modules.debugger.jpda.JPDADebuggerImpl.finish(JPDADebuggerImpl.java:1467)
        at org.netbeans.modules.debugger.jpda.actions.KillActionProvider.doAction(KillActionProvider.java:74)
        at org.netbeans.spi.debugger.ActionsProvider$1.run(ActionsProvider.java:112)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:577)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1030)