'Uncaught exception' error for JavaFX

My system: OpenSUSE Leap 16.0; JabRef 5.15 from https://jabref.org/download/linux_rpm; java-25-openjdk 25.0.1.0

Good day,
When I begin to enter data into a new entry, the error ‘Uncaught exception occurred in Thread[#40.JavaFX.Application Thread,5,main] occurs. Full details below. I have had this error frequently during the past years, with different versions of Jabref and of Opensuse. How could I get rid of this error?
Thank you, Daniel

java.lang.ClassCastException: class java.lang.String cannot be cast to class org.jabref.model.entry.Author (java.lang.String is in module java.base of loader 'bootstrap'; org.jabref.model.entry.Author is in module org.jabref@5.15.60000 of loader 'app')
	at org.jabref@5.15.60000/org.jabref.gui.autocompleter.PersonNameStringConverter.toString(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.cell.CellUtils.getItemText(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.cell.CellUtils.updateItem(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.cell.TextFieldListCell.updateItem(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.ListCell.updateItem(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.ListCell.indexChanged(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.IndexedCell$1.invalidated(Unknown Source)
	at javafx.base@22.0.1/javafx.beans.property.IntegerPropertyBase.markInvalid(Unknown Source)
	at javafx.base@22.0.1/javafx.beans.property.IntegerPropertyBase.set(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.IndexedCell.updateIndex(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.VirtualFlow.setCellIndex(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.VirtualFlow.getCell(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.VirtualFlow.getOrCreateCellSize(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.VirtualFlow.getOrCreateCellSize(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.VirtualFlow$5.invalidated(Unknown Source)
	at javafx.base@22.0.1/javafx.beans.property.IntegerPropertyBase.markInvalid(Unknown Source)
	at javafx.base@22.0.1/javafx.beans.property.IntegerPropertyBase.set(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.VirtualFlow.setCellCount(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.ListViewSkin.updateItemCount(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.skin.ListViewSkin.<init>(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.ListView.createDefaultSkin(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.Control.doProcessCSS(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.Control$1.doProcessCSS(Unknown Source)
	at javafx.controls@22.0.1/com.sun.javafx.scene.control.ControlHelper.processCSSImpl(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.scene.NodeHelper.processCSS(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Parent.doProcessCSS(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Parent$1.doProcessCSS(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.scene.ParentHelper.processCSSImpl(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.PopupControl$CSSBridgeHelper.superProcessCSSImpl(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.PopupControl$CSSBridgeHelper.superProcessCSS(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.PopupControl$CSSBridge.doProcessCSS(Unknown Source)
	at javafx.controls@22.0.1/javafx.scene.control.PopupControl$CSSBridgeHelper.processCSSImpl(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.scene.NodeHelper.processCSS(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Parent.doProcessCSS(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Parent$1.doProcessCSS(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.scene.ParentHelper.processCSSImpl(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.scene.NodeHelper.processCSS(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Node.processCSS(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Scene.doCSSPass(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Scene.preferredSize(Unknown Source)
	at javafx.graphics@22.0.1/javafx.scene.Scene$2.preferredSize(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.scene.SceneHelper.preferredSize(Unknown Source)
	at javafx.graphics@22.0.1/javafx.stage.Window$12.invalidated(Unknown Source)
	at javafx.base@22.0.1/javafx.beans.property.BooleanPropertyBase.markInvalid(Unknown Source)
	at javafx.base@22.0.1/javafx.beans.property.BooleanPropertyBase.set(Unknown Source)
	at javafx.graphics@22.0.1/javafx.stage.Window.setShowing(Unknown Source)
	at javafx.graphics@22.0.1/javafx.stage.Window.show(Unknown Source)
	at javafx.graphics@22.0.1/javafx.stage.PopupWindow.showImpl(Unknown Source)
	at javafx.graphics@22.0.1/javafx.stage.PopupWindow.show(Unknown Source)
	at org.jabref.merged.module@5.15.60000/impl.org.controlsfx.skin.AutoCompletePopup.show(Unknown Source)
	at org.jabref.merged.module@5.15.60000/org.controlsfx.control.textfield.AutoCompletionBinding.showPopup(Unknown Source)
	at org.jabref.merged.module@5.15.60000/org.controlsfx.control.textfield.AutoCompletionBinding$FetchSuggestionsTask.lambda$call$0(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(Unknown Source)
	at java.base/java.security.AccessController.doPrivileged(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
	at javafx.graphics@22.0.1/com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$10(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)

When I try to start JabRef as su with ‘opt/jabref/bin/JabRef’, the following error occurs:

2026-02-04 11:12:08 [main] org.jabref.Launcher.main()
ERROR: Unexpected exception: java.lang.UnsupportedOperationException: Unable to open DISPLAY
	at javafx.graphics@22.0.1/com.sun.glass.ui.gtk.GtkApplication.lambda$new$5(Unknown Source)
	at java.base/java.security.AccessController.doPrivileged(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.glass.ui.gtk.GtkApplication.<init>(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.glass.ui.gtk.GtkPlatformFactory.createApplication(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.glass.ui.Application.run(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.tk.quantum.QuantumToolkit.startup(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.application.PlatformImpl.startup(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.application.PlatformImpl.startup(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.application.LauncherImpl.startToolkit(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.application.LauncherImpl.launchApplication1(Unknown Source)
	at javafx.graphics@22.0.1/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)

Thanks for the report.
Can you please verify it the error is still present in the latest dev version?
https://builds.jabref.org/main/
Remember to make a backup of your library before trying out the new version.

Danke. Seltsamerweise kann ich den Fehler im Moment auch bei Jabref 15.5 nicht reproduzieren, obwohl er dauernd auftrat. Habe nur Kleinigkeiten in den Einstellungen geändert. Sobald der Fehler wieder auftritt, werde ich das neue Build ausprobieren. Übrigens trat der Fehler nicht auf, wenn ich die Eingabe ganz langsam durchführe.