✅ Winforms: open two forms at the same time

System.ArgumentException: 'Parameter is not valid.'

public void openImageScreenshot(string imageLocationPath, PictureBox pictureBox)
{
    SelectArea area = new SelectArea(this);
   
    area.BringToFront();
    area.Activate();
    
    using (Image img = Image.FromFile(imageLocationPath))
    {
        AspectRatioForm aspectRatioForm = new AspectRatioForm(img);
        aspectRatioForm.Show();
    }
    this.Hide();
    area.ShowDialog();
    // After showing and hiding the SelectArea form, you can access the file path:
    string imagePathScreenshot = area.GetScreenshotFilePath();
    pictureBox.ImageLocation = imagePathScreenshot;
    this.Show();
}