No global identifier provided: gtin, mpn, brand

Google wants a product ID that is the same everywhere the product is sold, such as the barcode number. It's a non-critical issue: add the GTIN if your products have one, and leave the warning if they don't.

A GTIN is the number under a product's barcode. In the US that's usually a 12-digit UPC. In Europe it's usually a 13-digit EAN. Books use an ISBN. Google uses it to know exactly which product you sell.

Google's help lists the same issue as No global identifier provided (e.g., gtin, mpn, isbn). Either way, it wants a gtin in one of its forms, an mpn, or an isbn.

Add the number you have

Before

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Canvas Weekender Bag",
  "image": "https://example.com/photos/weekender-bag.jpg",
  "offers": {
    "@type": "Offer",
    "price": 89,
    "priceCurrency": "USD",
    "availability": "https://schema.org/InStock"
  }
}
</script>

After: the 13-digit EAN from the barcode

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Canvas Weekender Bag",
  "image": "https://example.com/photos/weekender-bag.jpg",
  "gtin13": "4006381333931",
  "brand": {
    "@type": "Brand",
    "name": "Trailhead Goods"
  },
  "offers": {
    "@type": "Offer",
    "price": 89,
    "priceCurrency": "USD",
    "availability": "https://schema.org/InStock"
  }
}
</script>

Use the most specific field: gtin13 for an EAN, gtin12 for a UPC. gtin also works.
Write the number only. Google doesn't accept the GTIN as a URL.
No barcode, but the maker has a part number? Use mpn, with brand.
Don't make up a number. A wrong GTIN matches your product to someone else's.

When to leave it

Handmade goods, custom orders, and your own label often have no GTIN or part number. Then there's nothing to add, and the warning can stay. Merchant Center feeds have an identifier_exists attribute for this case. Google's markup docs list no such field, so the warning stays in Search Console.

Where the number lives

WooCommerce

Each product has a GTIN, UPC, EAN, or ISBN field on the Inventory tab. WooCommerce checks the number and, if it's valid, writes it as gtin in the product markup.

Shopify

Each variant has a Barcode field. Test a product in the Rich Results Test to see whether your theme or app writes it into the markup.

BigCommerce

Cornerstone writes the product's GTIN and MPN into the markup when they're set on the product.

Questions

Does "No global identifier provided" stop my products from showing?

No. It's a non-critical issue. Google's email says non-critical issues don't stop the page or feature from showing on Google.

Is a SKU a global identifier?

No. A SKU is your own stock code, so it differs from store to store. Google asks for a GTIN, MPN, or ISBN, which stay the same everywhere.

My products are handmade. What should I put?

Nothing. Leave the GTIN out and accept the warning. Never invent a number to clear it.

Sources

Checked on October 8, 2026. Vendors change their tools and docs, so check the source if something looks different.

"No global identifier provided (e.g., gtin, brand)": what it means