Merchant Center can flag a barcode that is valid but belongs to something else. The issues read "GTIN not related to brand", "Conflicting values (GTIN, brand)", "Incorrect GTIN" or "Incorrect product identifier". This guide explains what each one means, what causes them on Shopify and how to correct the data.
What the issues mean
These are different from "Invalid value [gtin]", which is about format. Here the number is a real GTIN, but Google thinks it does not fit the product or brand you sent.
| Issue | Meaning | Effect |
|---|---|---|
| GTIN not related to brand / Conflicting values (GTIN, brand) | The GTIN is not associated with the brand you submitted | Limited performance |
| Incorrect GTIN | The GTIN is valid, but incorrect for this product | Shown on Needs attention |
| Incorrect product identifier | You said the product has no identifier, but Google thinks it has a GTIN | Disapproved until fixed |
Common causes
Google's help pages name one cause above the rest: a GTIN from a different product accidentally reused. On Shopify, the GTIN comes from each variant's Barcode field and the brand from the Vendor field.
- Copied barcode: One variant's barcode pasted into another product
- Wrong vendor: A supplier or store name in Vendor instead of the manufacturer
- Compatible products: Google says to use the brand of whoever built the product, not the brand it fits
- identifier_exists set to no: On a product that does have a manufacturer GTIN
Find the affected products
In Merchant Center, open Products, go to the Needs attention tab and filter by the issue. Download the list as a .csv file and compare each GTIN and brand with the product's packaging. For US brands, Google points to the GS1 GEPIR tool to check who owns a GTIN.
Fix the data
Correct the source, which on Shopify means the variant Barcode field and the product Vendor field. For one product in Merchant Center, click its title, choose Edit product, correct the values and save. For many, fix the data and upload it again. Google says changes may take 24 to 72 hours to show on the Needs attention page.
- GTIN not related to brand: Confirm the brand is the real manufacturer and the GTIN is the one on the packaging
- Incorrect GTIN: Replace it with the manufacturer's GTIN for that exact product, and check the title, image and description match
- Incorrect product identifier: Add the valid GTIN and stop sending identifier_exists as no
Prevent it
Barcodes go wrong in bulk edits and supplier imports. Check a sample against packaging whenever you import products.
- ✅ The manufacturer's GTIN, one per variant
- ✅ The manufacturer's brand in Vendor
- ❌ Making up a GTIN. Google says if you are not sure, do not provide one
- ❌ Reusing one barcode across products
If you have no barcode at all, see GTIN, MPN and brand explained. For format errors, see [how to fix Invalid value [gtin]](/guides/fix-invalid-value-gtin-google-merchant-center).
Doing this at scale
FeedFix checks every product against Google Merchant Center and Meta Catalog rules and scores each one from 0 to 100 per channel, so you can see which products have data problems. It drafts compliant title and description rewrites you review as before/after diffs and apply in bulk, with every change audit-logged. See FeedFix.