SKU is associated to more than 1 GCID

SKU [card-game-7] is associated to more than 1 GCID, which is not allowed. Please send a delete feed for this SKU and all other SKUs with the same attribute values [merchant_suggested_asin], and then resubmit the SKUs

This error might appear when the product you want to link to Amazon, has already been added to your Amazon Seller account but with a different SKU. To fix this error, please make sure to adjust SKUs, so that they are the same on Shopify and Amazon. Try sending the item once more after doing this.

Another case might be when the same product barcode corresponds to two different products in the Amazon catalog. Each Amazon product page has its own ASIN and counts as a different product. Still, even different ASINs can represent a similar product with the same EAN code. When that happens, you can specify an ASIN directly in the Selling List to resolve this overlap. Check the ASIN in the product details section of the product that you want to sell on Amazon. Then open the Selling List with the item and paste it in the “Add ASIN” field. Try sending the product again after adding the code to link it.