Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException at javafx.fxml@21.0.2/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1858) at javafx.fxml@21.0.2/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1726) at javafx.base@21.0.2/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) at javafx.base@21.0.2/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:232) at javafx.base@21.0.2/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:189) at javafx.base@21.0.2/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) at javafx.base@21.0.2/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) at javafx.base@21.0.2/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base@21.0.2/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base@21.0.2/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base@21.0.2/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base@21.0.2/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base@21.0.2/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) at javafx.base@21.0.2/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) at javafx.base@21.0.2/javafx.event.Event.fireEvent(Event.java:198) at javafx.graphics@21.0.2/javafx.scene.Node.fireEvent(Node.java:8875) at javafx.controls@21.0.2/javafx.scene.control.Button.fire(Button.java:203) at javafx.controls@21.0.2/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:207) at javafx.controls@21.0.2/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274) at javafx.base@21.0.2/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:247) at javafx.base@21.0.2/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80) at javafx.base@21.0.2/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:232) at javafx.base@21.0.2/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:189) at javafx.base@21.0.2/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) at javafx.base@21.0.2/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) at javafx.base@21.0.2/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base@21.0.2/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base@21.0.2/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base@21.0.2/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base@21.0.2/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base@21.0.2/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) at javafx.base@21.0.2/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54) at javafx.base@21.0.2/javafx.event.Event.fireEvent(Event.java:198) at javafx.graphics@21.0.2/javafx.scene.Scene$MouseHandler.process(Scene.java:3984) at javafx.graphics@21.0.2/javafx.scene.Scene.processMouseEvent(Scene.java:1890) at javafx.graphics@21.0.2/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2708) at javafx.graphics@21.0.2/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:411) at javafx.graphics@21.0.2/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:301) at java.base/java.security.AccessController.doPrivileged(AccessController.java:399) at javafx.graphics@21.0.2/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:450) at javafx.graphics@21.0.2/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:424) at javafx.graphics@21.0.2/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:449) at javafx.graphics@21.0.2/com.sun.glass.ui.View.handleMouseEvent(View.java:551) at javafx.graphics@21.0.2/com.sun.glass.ui.View.notifyMouse(View.java:937) at javafx.graphics@21.0.2/com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at javafx.graphics@21.0.2/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:185) at java.base/java.lang.Thread.run(Thread.java:840) Caused by: java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:72) at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at javafx.base@21.0.2/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:270) at javafx.fxml@21.0.2/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:84) at javafx.fxml@21.0.2/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1853) ... 46 more Caused by: java.lang.NullPointerException: Cannot invoke "javafx.scene.control.Label.setText(String)" because "this.labelUserName" is null at MyApp.uiController.setUserNName(uiController.java:109) at MyApp.uiController.setUser(uiController.java:129) at MyApp.pageMain.sendUserToControler(pageMain.java:126) at MyApp.pageMain.logOrSign(pageMain.java:85) at MyApp.pageMain.clicked_buttonLogSignEnter(pageMain.java:69) ... 57 more