# Strange Java error **URL:** \ **Category:** Help\ **Created:** [May 17, 2022, 9:05am UTC](https://discourse.jabref.org/t/strange-java-error/3388 "2022-05-17T09:05:36Z")\ **Posts on this page:** 3\ **Page:** 1

**Author:** ![Lukas\_Flierl](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.jabref.org/lukas_flierl/32/730_2.png) [@Lukas\_Flierl](https://discourse.jabref.org/u/Lukas_Flierl)\ **Post date:** [May 17, 2022, 9:05am UTC](https://discourse.jabref.org/t/strange-java-error/3388/1 "2022-05-17T09:05:36Z")

Hi, I tried to open my bib file with JabRef, but some strange error occurs, and I receive an error message, which I do not understand and I really do not know how to describe it. See, " java.lang.NullPointerException at java.base/java.util.Objects.requireNonNull(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.entryeditor.FieldsEditorTab.(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.entryeditor.RequiredFieldsTab.(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.entryeditor.EntryEditor.createTabs(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.entryeditor.EntryEditor.(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.LibraryTab.(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.LibraryTab$Factory.createLibraryTab(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.importer.actions.OpenDatabaseAction.openTheFile(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.importer.actions.OpenDatabaseAction.openFiles(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.importer.actions.OpenDatabaseAction.openFile(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.menus.FileHistoryMenu.openFile(Unknown Source) at org.jabref@5.6.60000/org.jabref.gui.menus.FileHistoryMenu.lambda$addItem$0(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventUtil.fireEventImpl(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventUtil.fireEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/javafx.event.Event.fireEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/javafx.scene.control.MenuItem.fire(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.scene.control.ContextMenuContent$MenuItemContainer.doSelect(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.scene.control.ContextMenuContent$MenuItemContainer.lambda$createChildren$12(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventUtil.fireEventImpl(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.event.EventUtil.fireEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/javafx.event.Event.fireEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/javafx.scene.Scene$MouseHandler.process(Unknown Source) at org.jabref.merged.module@5.6.60000/javafx.scene.Scene.processMouseEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/javafx.scene.Scene$ScenePeerListener.mouseEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source) at java.base/java.security.AccessController.doPrivileged(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.glass.ui.View.handleMouseEvent(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.glass.ui.View.notifyMouse(Unknown Source) at org.jabref.merged.module@5.6.60000/com.sun.glass.ui.win.WinApplication.\_runLoop(Native Method) at org.jabref.merged.module@5.6.60000/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(Unknown Source) at java.base/java.lang.Thread.run(Unknown Source) " Any ideas? ---

**Author:** ![ThiloteE](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.jabref.org/thilotee/32/1008_2.png) [@ThiloteE](https://discourse.jabref.org/u/ThiloteE)\ **Post date:** [May 17, 2022, 10:57am UTC](https://discourse.jabref.org/t/strange-java-error/3388/2 "2022-05-17T10:57:05Z")

I don’t know what the error message could be about but I know a working strategy how to find out: 1. Remove stuff from your library until no error message pops anymore. - How? Open your library with a [text editor](https://alternativeto.net/software/notepad-plus-plus/?license=opensource) and then delete stuff. - Use the 50% approach. Delete 50%, then another 50% of the remaining 50% and another half and another half, and so on. Doing this a few times will allow you to pretty fast corner the problem. 2. There is no second step apart from posting your results. It’s all about the first step xD ---

**Author:** ![Siedlerchr](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.jabref.org/siedlerchr/32/216_2.png) [@Siedlerchr](https://discourse.jabref.org/u/Siedlerchr)\ **Post date:** [May 17, 2022, 6:48pm UTC](https://discourse.jabref.org/t/strange-java-error/3388/3 "2022-05-17T18:48:07Z")

Hi, the error seems to be coming from opening a file and displaying the library with the entry editor. Something is null (not present) which should be there… Strange. Never encountered before. Is it possible to provide us the bib file (you can send it privately to [web@jabref.org](mailto:web@jabref.org))