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Limited performance due to missing identifiers [gtin, mpn, brand] on Shopify: what to fill in

ARLing s. r. o. · 20 October 2026

Limited performance due to missing identifiers [gtin, mpn, brand] is a Google Merchant Center message that Shopify merchants ask about on the Shopify Community forum, and one of them sees it in the Shopify admin next to the Google & YouTube channel. Google's help article with that title, archived on 16 July 2024, now leads from the same address to How to fix: Missing or incorrect GTIN, with the same advice: add a brand and either a GTIN or an MPN, while a one-of-a-kind or vintage product needs no identifier. These identifiers come from the manufacturer, and Google asks you not to make them up, guess them or copy them from similar products. This note shows where each identifier goes in Shopify, what to do when a product has none, and what our free public check can and cannot see.

What Google is asking for

Google shows the message when a value for a unique product identifier is missing or isn't recognized as valid; depending on the target country and the product category, Google may require identifiers or a statement that they don't exist. The identifiers are the GTIN, the MPN and the brand, and because the manufacturer assigns them, the same product has the same identifiers at every retailer.

Google strongly recommends a GTIN for widely manufactured products, and a product that has a GTIN but is submitted without one may have limited visibility; the same applies to the brand and the MPN. Merchant Center lists the affected products under Products on the Needs attention tab, with a filter and a.csv download, and a fix shows there with a delay.

If the product has a GTIN: the barcode field in Shopify

In the Shopify admin, barcodes are entered on the product page in the Inventory section, and a product or a variant can have up to 20 of them. The GTIN is on the packaging above or below the barcode, you can request it from the manufacturer, and for products you make yourself, Shopify points to the GS1 website for how to get one. Choose the barcode type that matches the number: GTIN takes 8, 12, 13 or 14 digits, and Custom, the default, takes any value.

For the Google & YouTube channel, a product that has a GTIN needs it before it can be published, in the details of a product variant. In a product CSV file, the Barcodes column takes the type before the value with a colon, for example gtin:00012345678905, and a value without a type is imported as Custom.

If there is no GTIN: MPN and brand, or a custom product

Shopify's help for the Google & YouTube channel says that a product without a GTIN needs an MPN and a brand in the channel's product data. Google describes the steps: in your Shopify admin go to Sales channels > Google & YouTube > Products > All products, select the products, click Edit in bulk editor, fill in the fields and save; variants are updated in the Variants section of the product page.

If a product has no GTIN or MPN because it is a custom product, Google's steps for the app say to check This is a custom product. Google names custom goods, one-of-a-kind products such as art or handmade goods, and products made before GTINs existed, such as vintage products, antiques and books published before 1970, among products that might not have identifiers. For a new product without assigned identifiers, Google asks for the identifier_exists attribute set to no or false.

If you make the product yourself and have no official brand, Google's guidance is to use your store name as the brand, with an MPN of your choice. Shopify's CSV description has a similar rule for the Vendor column: for a product you make yourself, it holds the store name you use to log in to Shopify. The pages we read don't say whether the Google & YouTube app sends the vendor as the brand, so fill in the brand in the channel's product data, as Shopify's channel help asks.

Which case is your product?

Your productWhat Google asks forWhere in Shopify
Has a manufacturer GTINThe GTINBarcodes, in the Inventory section of the product or variant
No GTIN, but a manufacturer part numberAn MPN together with a brandThe Google & YouTube channel's product data
Made by you, without an official brandYour store name as the brand with an MPN of your choice, or identifier_exists set to false for custom goodsThe Google & YouTube channel's product data, or This is a custom product

A one-of-a-kind or vintage product needs no identifier, according to Google. The app steps we found describe the checkbox This is a custom product only for custom products, so check how a vintage item shows in Merchant Center after you sync it.

Whatever the case, Google warns that incorrect identifiers can get products disapproved, and that an identifier you don't have should stay blank rather than be filled with an internal SKU or another value specific to your store.

Frequently asked questions

Can I use my SKU as the MPN?

Not in place of the manufacturer's number: if a product has assigned identifiers that you don't have, Google says to leave the attribute blank rather than use internal SKUs or other values specific to your store. If you are the manufacturer and have no official brand, Google allows your store name as the brand with an MPN of your choice.

My products are handmade. Do I need a GTIN?

Google names custom goods and handmade goods among products that might not have unique identifiers, and asks for identifier_exists set to no or false for a product whose condition is new and that has no assigned identifiers. In the Google & YouTube app, Google's steps for a custom product without a GTIN or MPN are to check This is a custom product.

Does the free public check see my barcodes?

Usually not: in our study, the public product export showed no barcodes for any of the 113 stores, so the check reports barcodes as unknown rather than missing, and it flags an invalid check digit only on a published GTIN. It did find a vendor on every sampled product of the 110 stores whose export could be read.

See what your public product data shows

Our free public check needs no install and no e-mail; it reads up to 20 products from your public product export and shows, rule by rule, how many of the checked items are affected. Barcodes that the export does not show stay unknown there. Our Shopify app, Agentic Product Check, checks the GTIN check digit of barcodes and empty vendor fields in your admin, but it is waiting for Shopify App Store approval and cannot be installed yet.

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Sources. The facts in this note are numbered after our internal fact list and were checked on the publication date. If a source has changed since, write to support@arling.sk and we will correct this page.