leehaut opened a new issue, #7753:
URL: https://github.com/apache/hop/issues/7753
### Apache Hop version?
2.19.0
### Java version?
jdk21
### Operating system
Windows
### What happened?
## Description
When using Hop GUI, an intermittent
`java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0`
can appear in the event loop (sometimes noticed while closing the UI).
Stack trace example:
```txt
2026/08/02 10:37:33 - Hop - Projects enabled
2026/08/02 10:37:33 - Hop - Enabling project : 'hop_demo'
2026/08/02 10:37:33 - Hop - Two-way password encoder initialized with plugin
ID 'Hop' for project 'hop_demo'
Error in the Hop GUI : Index 0 out of bounds for length 0
java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0
at
org.apache.hop.core.undo.ChangeAction.setPosition(ChangeAction.java:213)
at org.apache.hop.base.AbstractMeta.addUndo(AbstractMeta.java:500)
at
org.apache.hop.ui.hopgui.delegates.HopGuiUndoDelegate.addUndoPosition(HopGuiUndoDelegate.java:65)
at
org.apache.hop.ui.hopgui.file.pipeline.HopGuiPipelineGraph.mouseUp(HopGuiPipelineGraph.java:1254)
at
org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:262)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4364)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1217)
at
org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4162)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3750)
at org.apache.hop.ui.hopgui.HopGui.open(HopGui.java:619)
at org.apache.hop.ui.hopgui.HopGui.main(HopGui.java:453)
```
### Issue Priority
Priority: 3
### Issue Component
Component: Hop Gui
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