The supplied GTIN/UPC/EAN/ISBN value fails Pinterest's checksum or length validation and is rejected.
Pinterest Catalogs uses identifiers (GTIN, MPN, brand, SKU) to match catalog records. Issues come from invalid format (non-numeric in a GTIN field), brand-GTIN mismatches in GS1's database, duplicate IDs across SKUs, or missing required identifiers for the category.