To reproduce run following code. You will get exception.

public class GroupApp extends Application {

    @Override
    public void start(Stage primaryStage) {

        StackPane root = new StackPane();
        Group g = new Group();
        DoubleProperty d = new SimpleDoubleProperty(0);
        g.layoutXProperty().bind(d);
        root.getChildren().add(g);

        Scene scene = new Scene(root, 500, 500);

        primaryStage.setScene(scene);
        primaryStage.show();
        TimelineBuilder.create().keyFrames(new KeyFrame(Duration.seconds(6), new KeyValue(d, 10))).build().play();
    }
    public static void main(String[] args) {
        launch(args);
    }
}

///exception


Caused by: java.lang.RuntimeException: A bound value cannot be set.
at javafx.beans.property.DoublePropertyBase.set(DoublePropertyBase.java:159)
at javafx.scene.Node.setLayoutX(Node.java:2153)
at javafx.scene.Node.relocate(Node.java:2257)
at javafx.scene.layout.Region.position(Region.java:2033)
at javafx.scene.layout.Region.layoutInArea(Region.java:2014)
at javafx.scene.layout.Region.layoutInArea(Region.java:1915)
at javafx.scene.layout.StackPane.layoutChildren(StackPane.java:348)
at javafx.scene.Parent.layout(Parent.java:1018)
at javafx.scene.Scene.layoutDirtyRoots(Scene.java:513)
at javafx.scene.Scene.doLayoutPass(Scene.java:484)
at javafx.scene.Scene.preferredSize(Scene.java:1455)
at javafx.scene.Scene.impl_preferredSize(Scene.java:1482)
at javafx.stage.Window$10.invalidated(Window.java:719)
at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:127)
at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:161)
at javafx.stage.Window.setShowing(Window.java:782)
at javafx.stage.Window.show(Window.java:797)
at javafx.stage.Stage.show(Stage.java:229)
at javafxapplication11.GroupApp.start(GroupApp.java:37)