Django Rest Framework 'RelatedManager' object has no attribute

The original error is: ``` Got AttributeError when attempting to get a value for field `original` on serializer `ProductImageSerializer`. The serializer field might be named incorrectly and not match any attribute or key on the `RelatedManager` instance. Original exception text was: 'RelatedManager' object has no attribute 'original'. ``` This is my `models.py`: ``` class Product(models.Model): name = models.CharField(max_length=100, db_index=True) ean = models.CharField(max_length=13, db_index=True) ... class ProductImage(models.Model): product = models.ForeignKey(Product, null=True, related_name='images', on_delete=models.CASCADE, db_index=True) original = models.ImageField(upload_to=get_uuid_image) medium = models.ImageField(upload_to=get_uuid_image) small = models.ImageField(upload_to=get_uuid_image) ``` The serializers: ``` class ProductBasicSerializer(serializers.ModelSerializer): tags = TagSerializer(many=True) brand = BrandSerializer() images = ProductImageSerializer(required=False) class Meta: model = Product fields = ['tags', 'brand', "ean", "name", "quantity", "unit", "images"] class ProductImageSerializer(serializers.ModelSerializer): class Meta: model = ProductImage exclude = ("product",) ``` And in the view: ``` product = Product.objects.get(ean=ean) serializer = ProductBasicSerializer(product) ``` Why do I get the error `RelatedManager' object has no attribute 'original'` ? The reverse relationship ProductImage, with `related_name="images"` does have the attribute `original`.