javafx.fxml.LoadException Exception in Application start method

Question

I try to clone (gitHub) my project from my laptop to my desktop computer and i have an "Exception in Application start method". it works fine in my laptop.

All the dependencies are setup, i tried to create and open a little test project and it's ok with the same referenced libraries.

I try to resolve it by myself since yesterday with google but i failed. So maybe someone here can understand what's wrong with my code and help me.

All files are in the same package. Every path:" " are Relative Paths.

and at line 40 :

Parent root = Parent root = FXMLLoader.load(getClass().getResource("fr/oz/main/mainWindow.fxml"));

Here my Terminal:

Exception in Application start method
java.lang.reflect.InvocationTargetException
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:119)
        at java.base/java.lang.reflect.Method.invoke(Method.java:577)
        at javafx.graphics@18.0.1/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:465)
        at javafx.graphics@18.0.1/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:364)
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
        at java.base/java.lang.reflect.Method.invoke(Method.java:577)
        at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1081)
Caused by: java.lang.RuntimeException: Exception in Application start method
        at javafx.graphics@18.0.1/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:901)
        at javafx.graphics@18.0.1/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
        at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.NullPointerException: Location is required.
        at javafx.fxml@18.0.1/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3324)
        at javafx.fxml@18.0.1/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3287)
        at javafx.fxml@18.0.1/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3255)
        at javafx.fxml@18.0.1/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3227)
        at javafx.fxml@18.0.1/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3203)
        at javafx.fxml@18.0.1/javafx.fxml.FXMLLoader.load(FXMLLoader.java:3196)
        at fr.oz.main.App.start(App.java:40)
        at javafx.graphics@18.0.1/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
        at javafx.graphics@18.0.1/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
        at javafx.graphics@18.0.1/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
        at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
        at javafx.graphics@18.0.1/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
        at javafx.graphics@18.0.1/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
        at javafx.graphics@18.0.1/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at javafx.graphics@18.0.1/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
        ... 1 more
Exception running application fr.oz.main.App

and my main Class

package fr.oz.main;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class App extends Application {
   public static void main(String[] args) {
       launch(args);
   }

   

   @Override
   public void start(Stage primaryStage) throws Exception {
       Parent root = FXMLLoader.load(getClass().getResource("fr/oz/main/mainWindow.fxml"));
       Scene scene = new Scene(root);
       primaryStage.setScene(scene);
      

   }

}

Thanks