Undo image shows Parameter is not valid

public class ImageHandler
    {
        private Bitmap _currentBitmap;
        private Bitmap _bitmapbeforeProcessing;

        public Bitmap CurrentBitmap
        {
            get
            {
                if (_currentBitmap == null)
                {
                    _currentBitmap = new Bitmap(1, 1);
                }
                return _currentBitmap;
            }
            set { _currentBitmap = value; }
        }

        public string CurrentBitmapPath { get; set; }

        public void ResetBitmap()
        {
            if (_currentBitmap != null && _bitmapbeforeProcessing != null)
            {
                 Bitmap temp = (Bitmap)_currentBitmap.Clone();
                _currentBitmap = (Bitmap)_bitmapbeforeProcessing.Clone();
                _bitmapbeforeProcessing = (Bitmap)temp.Clone();
            }
        }


        internal void RestorePrevious()
        {
            _bitmapbeforeProcessing = _currentBitmap;
        }

     }

    public class RotationHandler
      {
       private ImageHandler imageHandler;

  
        public void Flip(RotateFlipType rotateFlipType)
        {
         this.imageHandler.RestorePrevious();
         Bitmap bitmap = (Bitmap) this.imageHandler.CurrentBitmap.Clone();
         this.imageHandler.CurrentBitmap.Dispose(); // dispose of current bitmap
         bitmap.RotateFlip(rotateFlipType);
         this.imageHandler.CurrentBitmap = bitmap;
       }

     }