Why identifiers matter
GTIN, MPN and brand are how Google knows exactly which product you sell. With them Google can match your listing to searches for that product and show richer results. Without them, a product that has an assigned GTIN can be limited or disapproved.
Which rule applies to your product
- It has a manufacturer barcode (UPC, EAN, ISBN or JAN): submit it as the GTIN, exactly as printed. Never guess or reuse one from a similar product.
- You make it yourself and you are the only seller: Google's brand guidance is to use your store name as the brand and submit an MPN of your choice, rather than setting identifier_exists to no.
- It truly has no GTIN, MPN or brand, such as a custom, handmade or vintage item: set identifier_exists to no.
- It is a generic product from a supplier with no clear brand: only submit a brand if you are sure it is correct. Google says not to guess or make one up.
Don't misuse identifier_exists
Setting identifier_exists to no on a product that does have an identifier is not a shortcut. Google says it may warn or limit products where it finds evidence that a unique identifier exists.
How to fix many products at once
Fix identifiers where they come from, usually the barcode or SKU fields in Shopify, so the next feed fetch carries them. If you can't change the source, a supplemental data source keyed on product ID can add the GTIN, MPN or identifier_exists value for each product.
How UltraROAS.ai does this for you
UltraROAS.ai flags products with no GTIN or MPN, ranked by the spend they affect, and explains which fix applies. It never writes or changes identifiers itself, because only you know a product's real barcode.