Shopify products without barcodes: how to fix missing GTIN errors in Merchant Center
If your Shopify products have no barcode, Google may flag missing GTINs. Add real barcodes where they exist, and mark the rest so Google stops asking for them.
The short answer
If a product has a manufacturer barcode, enter it in the variant's barcode field in Shopify. If it has none, because you make it yourself or it is one of a kind, give Google a brand and MPN or tell Google no identifier exists. In the Google & YouTube app, that last option is the custom product setting. Never invent a barcode to make the error go away.
What Google is asking for
Google's GTIN attribute page says GTIN is recommended for every product that has one assigned by the manufacturer. UPC, EAN, JAN, ISBN and ITF-14 are all GTINs. Products with missing or incorrect GTINs may get limited visibility.
The issue you will usually see is Missing or incorrect GTIN. The same Google help page used to be titled "Limited performance due to missing identifiers", and many forum threads still use that name. Google's fix is that each product needs "either an accurate GTIN" or both an MPN and a brand. For one-of-a-kind or vintage products, Google says you don't need an identifier and should set identifier_exists to false.
Shopify's Google & YouTube channel requirements are stricter in wording: if a product has a GTIN, add it before publishing.
Step 1: sort your catalog into three groups
- Branded goods you resell. These almost always have a GTIN printed on the box or in the supplier's spreadsheet. Get it.
- Your own brand, made for you. If you registered barcodes with GS1, use them. If not, Google's page says store brands and products only you sell generally don't have a GTIN, so you submit brand and MPN instead.
- Handmade, custom or vintage. No GTIN exists. Mark them as custom.
Step 2: add real barcodes in Shopify
Shopify's barcode guide gives two paths:
- Product without variants. Open the product, then in the Inventory section click the Barcodes field and enter the number.
- Product with variants. In the Variants section, select the variants, open the menu and choose Edit barcodes, then add one per variant.
Each variant needs its own barcode. A red medium and a blue large are different products with different GTINs. A Shopify Community answer in a thread on GTIN errors after entering barcodes confirms the barcode field is where merchants put the GTIN for the Google channel.
Check digits before you save. Google says a GTIN must be 8, 12, 13 or 14 digits with a correct check digit, and rejects restricted prefixes 02, 04 and 2 and coupon prefixes 05, 98 and 99. A valid number from the wrong product causes a different issue, Incorrect GTIN, which Google says often happens when a GTIN from another product is reused by accident.
Step 3: mark products that have no GTIN
Google's guide to syncing products from the Google & YouTube app gives this path at the time of writing (November 2026):
- In Shopify, go to Sales channels > Google & YouTube.
- Select Products, then All products.
- Check the products, select Edit in bulk editor.
- For products with no GTIN or MPN, check This is a custom product. For products with a brand and MPN, fill those in instead.
- Select Save.
Google's identifier_exists page has a warning: only say no identifier exists if you are certain. If Google finds evidence that a GTIN exists, the product gets a warning. Marking a branded product you resell as custom is the wrong fix.
When the setting doesn't stick
Merchants have reported the custom flag not reaching Merchant Center. In a 2021 bug report thread, products marked custom were still disapproved. Workarounds in that thread included a Merchant Center feed rule that clears brand, MPN and GTIN and sets identifier_exists to no, followed by forcing the app to resend data. Posters said the rule alone was not enough until the data was resent.
A 2022 to 2023 thread reports similar problems and quotes support calling the custom flag not being sent "a known issue". These threads are old and the app has changed since. If you still hit it, the workarounds there are worth trying, but check the current state of your products in Merchant Center first.
If you fix GTINs only inside Merchant Center, expect them to come back. Google's Shopify shipping guide warns that Shopify or other API updates may overwrite manual changes made in Merchant Center. Product data comes from Shopify too, so fix it there or in the app's product data.
Where to get barcodes if you need them
For products you manufacture, Shopify's barcode guide points you to the GS1 standards website. Barcodes from GS1 are registered to your company. Google's GTIN page is direct about the alternative: "When in doubt don't provide a GTIN (for example, don't guess or make up a value)."
Other tools
- Merchant Center's Needs attention tab lets you filter by the GTIN issue and download a CSV of affected products.
- Feed apps such as Simprosys Google Shopping Feed are an alternative to the Google & YouTube app for sending product data. Merchants in the threads above suggested feed apps when the custom flag would not sync.
If products are not reaching Merchant Center at all, read why Merchant Center is not syncing with Shopify. Google's sync guide says products need identifiers before they can sync.