java.lang.IllegalStateException: Some of a set of deleted nodes are not present in the original ones. See #15478; you may need to check that your Children.Keys keys are safely comparable. i: 0 j: 0 This: org.openide.nodes.NodeMemberEvent[node=org.openide.nodes.LazyNode@712ba37a[Name=, displayName=Servers], add=true 0 at 0 = org.openide.nodes.FilterNode@46266496[Name=, displayName=Please Wait...] ] curr. snapshot: org.openide.nodes.EntrySupport$Default$DefaultSnapshot [] prev. snapshot: org.openide.nodes.EntrySupport$Default$DefaultSnapshot [] Current state: [] Delta: [org.openide.nodes.FilterNode@46266496[Name=, displayName=Please Wait...]] at org.openide.nodes.NodeMemberEvent.getDeltaIndices(NodeMemberEvent.java:176) at org.openide.explorer.view.VisualizerNode.childrenAdded(VisualizerNode.java:355) Caused: java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:0) 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.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:451) Caused: java.lang.reflect.UndeclaredThrowableException at $Proxy6.childrenAdded(.java:0) at org.openide.nodes.Node.fireSubNodesChange(Node.java:1093) at org.openide.nodes.EntrySupport$Default.notifyAdd(EntrySupport.java:686) at org.openide.nodes.EntrySupport$Default.updateAdd(EntrySupport.java:512) at org.openide.nodes.EntrySupport$Default.setEntries(EntrySupport.java:344) at org.openide.nodes.Children$Keys$2.run(Children.java:1503) at org.openide.util.Mutex.postRequest(Mutex.java:1262) at org.openide.util.Mutex.postRequest(Mutex.java:1209) at org.openide.util.Mutex.postWriteRequest(Mutex.java:582) at org.openide.nodes.Children$Keys.applyKeys(Children.java:1512) at org.openide.nodes.Children$Keys.setKeys(Children.java:1493) at org.openide.nodes.FilterNode$Children$DefaultSupport.updateKeys(FilterNode.java:1697) at org.openide.nodes.FilterNode$Children$DefaultSupport.update(FilterNode.java:1679) at org.openide.nodes.FilterNode$Children.addNotifyImpl(FilterNode.java:1473) at org.openide.nodes.FilterNode$Children.changeOriginal(FilterNode.java:1391) at org.openide.nodes.FilterNode.changeOriginal(FilterNode.java:447) at org.openide.nodes.LazyNode$1.run(LazyNode.java:89) at org.openide.util.Mutex$1Exec.run(Mutex.java:1239) at org.openide.nodes.Children$ProjectManagerDeadlockDetector.execute(Children.java:1810) at org.openide.util.Mutex.postRequest(Mutex.java:1245) at org.openide.util.Mutex.postRequest(Mutex.java:1209) at org.openide.util.Mutex.postWriteRequest(Mutex.java:582) at org.openide.nodes.LazyNode.switchToOriginal(LazyNode.java:86) at org.openide.nodes.LazyNode$SwitchChildren.getNodesCount(LazyNode.java:116) at org.openide.explorer.view.TreeView$6.run(TreeView.java:913) at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:577) at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1030)