Google Merchant Center: Missing GTIN
Limited performance due to missing value [gtin]What's happening
Google Merchant requires a GTIN (Global Trade Item Number, UPC, EAN, JAN, ISBN) for branded products from manufacturers that assign them. Most consumer goods qualify. As of late 2023 missing GTIN is a warning rather than disapproval, products still serve, but visibility in Shopping results is downgraded. The "Limited performance" warning is one of the highest-volume diagnostics in Merchant Center.
gtinidentifier_existsManual fix
Look up the GTIN for every product (often printed on the packaging or available in the manufacturer catalog), enter it into your CMS, propagate through your feed.
Fix it with Emberfeed
Use a conditional field rule: if g:gtin is empty AND product matches a brand pattern, set g:identifier_exists to "false" so Google accepts the omission. For known brands with available GTINs, build a lookup CSV and use a template rule to populate from a custom_label. One rule, applied to every matching product, no per-SKU edits.
Related guide
Related rejections
Catch Google Merchant Center feed issues before they do.
Emberfeed checks every product against Google Merchant Center's required fields and format rules, and most problems come with a fix: a field rule for the whole feed or an override for one product. It also measures your product photos, while rendering them and in the background after each refresh, and flags the ones that are too small for Google Merchant Center.
Emberfeed is a hosted tool: it imports your existing product feed, renders every product image through one template and serves a new feed URL for Meta, Google, TikTok, Heureka, Zboží.cz and Glami. It costs 25 € per feed per month, and the first 3 months are free on one feed up to 1,000 products.