A generic error occured in gdi+

private void GenerateThumbnails(double scaleFactor, Stream sourcePath,string targetPath)
{
       using (var image = System.Drawing.Image.FromStream(sourcePath))
        {
           // can given width of image as we want
           var newWidth = (int)(image.Width * scaleFactor);
           // can given height of image as we want
           var newHeight = (int)(image.Height * scaleFactor);
           var thumbnailImg = new Bitmap(newWidth, newHeight);
           var thumbGraph = Graphics.FromImage(thumbnailImg);
           thumbGraph.CompositingQuality = CompositingQuality.HighQuality;
           thumbGraph.SmoothingMode = SmoothingMode.HighQuality;
           thumbGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
           var imageRectangle = new Rectangle(0, 0, newWidth, newHeight);
           thumbGraph.DrawImage(image, imageRectangle);
           thumbnailImg.Save(targetPath, image.RawFormat);
       }
}