breakpoint when entering the line does not enter and gives an error

Question

Product when I put the breakpoint to the following code. You can jump into the insert line and get a null exception message.

public ActionResult Create([Bind(Include = "ID,Name,CategoryId,Brand,Model,ImageUrl,Description,Price, Tax,Discount,Stock, IsActive,CreateDate,CreateUserId,UpdateDate,UpdateUserId")] Product product, IEnumerable files)

if (files != null&&files.Count()>0)
            {

                foreach (var item in files)
                {


                    Tuple<string, string> paths = ImageUpload.SaveImageWithThumbnail(item, 329, 380, 84, 84, false);

                    product.Images.Add(new Images

                    {
                        ImageUrl = paths.Item1,

                        ImageUrlt = paths.Item2,
                        RegisterDate = DateTime.Now,
                        CreateDate = DateTime.Now,
                        CreateUserId = 1,
                        UpdateDate = DateTime.Now,
                        UpdateUserId = 1

                    });
                }
            }

            **db.Products.Add(product);**
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        ViewBag.CategoryId = new SelectList(db.Categories, "ID", "Name", product.CategoryId);
        return View(product);
    }