A product is missing the required Offer_ID (or 'id') value. Microsoft Merchant Center cannot ingest items without a unique offer identifier.
Microsoft Merchant Center 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.