How to Fix Missing GTIN, Brand and MPN in Google Merchant Center for WooCommerce

Fixing missing GTIN, brand and MPN in Google Merchant Center for WooCommerce

Fix missing GTIN, brand and MPN in Google Merchant Center for WooCommerce by mapping accurate product identifiers instead of inventing, guessing or reusing values that belong to another product.

Unique product identifiers help Google determine which commercial product a WooCommerce store is offering. When the submitted GTIN, brand or MPN is missing, inaccurate or assigned to the wrong variation, Merchant Center may display a warning, limit the product’s eligibility or disapprove the offer.

The correct solution depends on the product.

A mass-produced item with a manufacturer-assigned barcode should normally be submitted with its genuine GTIN and recognizable brand. A product without a manufacturer-assigned GTIN may require its brand and MPN. A genuinely handmade, vintage, custom or one-of-a-kind product may have no assigned identifiers and therefore require a different configuration.

The objective is not to fill every identifier field. It is to submit only the identifiers that truthfully belong to the exact product or variation being sold.

The short answer

When Google Merchant Center reports a missing or incorrect product identifier:

• Open the affected product under “Needs attention.”
• Record its offer ID, source and reported issue.
• Match the offer to the correct WooCommerce product or variation.
• Check the physical product, packaging and manufacturer documentation.
• Submit the manufacturer-assigned GTIN when one exists.
• Use the product’s recognized brand rather than automatically using the store or supplier name.
• Submit the manufacturer-assigned MPN when applicable.
• Keep leading zeros in GTIN values.
• Do not use a WooCommerce SKU as a GTIN.
• Do not invent a barcode or copy one from a similar product.
• Do not use the parent product’s GTIN for every variation.
• Set identifier_exists to false only when the product genuinely has no applicable unique product identifiers.
• Correct the source data that controls future updates.
• Resynchronize the affected product.
• Allow Merchant Center time to process the correction.
• Confirm that the issue disappears from “Needs attention.”

Google’s current unique product identifier guidance explains that common identifiers include GTIN, MPN and brand. These values must accurately identify the product being offered.

What are unique product identifiers?

Unique product identifiers, commonly abbreviated as UPIs, distinguish one commercial product from another.

The main identifiers used by Google Merchant Center are:

• GTIN
• Brand
• MPN

These fields are related, but they are not interchangeable.

A GTIN identifies a specific trade item using a standardized global numbering system. A brand identifies the recognized manufacturer or commercial brand associated with the product. An MPN identifies a specific product within that manufacturer’s own catalogue.

Accurate identifiers can help Google:

• Understand what the merchant is selling
• Match the offer with recognized product information
• Distinguish similar products from different manufacturers
• Connect equivalent offers from different retailers
• Associate the correct product details and reviews
• Identify specific variations
• Detect potentially inaccurate product data

Identifiers are factual product data. They are not fields for promotional keywords, category descriptions, internal notes or search-engine optimization phrases.

What is a GTIN?

GTIN means Global Trade Item Number.

It is the number normally printed below a product barcode. Depending on the product type and market, it may appear as:

• UPC or GTIN-12
• EAN or GTIN-13
• JAN
• ISBN-13
• ITF-14
• Another valid GTIN format supported by Google

Google’s GTIN documentation requires merchants to use the value assigned to the product by its manufacturer.

A WooCommerce store must not create its own GTIN for a branded product. The store is reselling the manufacturer’s item, not issuing a new global identity for it.

The correct GTIN may be found:

• Below the barcode on the product
• On the retail packaging
• On a book cover
• In an authorized manufacturer catalogue
• In official supplier documentation
• In the manufacturer’s product database
• By contacting the manufacturer or authorized distributor

Google’s guide to finding a GTIN provides examples of common barcode formats.

Why a WooCommerce SKU is not a GTIN

A WooCommerce SKU is normally an internal stock-keeping reference created by the store.

For example, a merchant may create:

SHOE-BLACK-42

This can be useful for inventory, order processing and warehouse operations. However, it is not a GTIN merely because it uniquely identifies the item inside that WooCommerce store.

A GTIN is assigned through the manufacturer’s recognized product-identification process. It must follow the applicable structure and validation requirements.

Do not place a WooCommerce SKU in the GTIN field to make a warning disappear.

The values could happen to look similar, but they serve different purposes:

• SKU identifies an item inside the merchant’s own system.
• GTIN identifies a standardized commercial product.
• MPN identifies an item within the manufacturer’s product range.
• Merchant Center offer ID identifies the submitted offer.

Keeping these identities separate makes product updates and troubleshooting more reliable.

What is a brand?

The brand attribute should contain the recognizable brand associated with the product.

For a branded commercial item, use the brand customers would reasonably recognize. Do not automatically use:

• The WooCommerce store name
• The website domain
• The distributor’s company name
• The importing company
• The supplier’s name
• The product category
• “Generic”
• “No brand”
• A marketing phrase

If a store sells a Samsung television, the brand should normally identify Samsung rather than the WooCommerce retailer that sells it.

Google’s current brand attribute guidance states that merchants should use the product brand generally recognized by online shoppers.

The store name can be appropriate when the merchant is genuinely the manufacturer, owns the private-label brand or sells products manufactured and branded specifically for that business.

A product should not be assigned the store’s brand merely because the correct manufacturer information is unavailable.

What is an MPN?

MPN means Manufacturer Part Number.

It is an alphanumeric value assigned by the manufacturer to distinguish a product from its other products. The combination of brand and MPN can identify a commercial item when a manufacturer-assigned GTIN is not available.

An MPN might look like:

AB-1048-BLK

The precise format is determined by the manufacturer.

According to Google’s MPN requirements, the MPN should be supplied for products without a manufacturer-assigned GTIN when an MPN exists. Google also warns merchants not to guess or create an MPN unless they are the manufacturer.

A distributor, wholesaler or WooCommerce retailer should not replace the manufacturer’s MPN with an internal stock reference.

When an SKU and MPN appear to match

Some manufacturers and retailers may use the manufacturer’s part number as their local SKU. In that situation, the visible values can be identical.

The matching text does not mean every SKU is automatically an MPN.

Before reusing an SKU in the MPN field, confirm that:

• The value was assigned by the manufacturer.
• The manufacturer uses it for the exact product.
• It is not merely an internal warehouse reference.
• It belongs to the correct variation.
• It has not been shortened or reformatted.
• It is associated with the submitted brand.

If that evidence is unavailable, do not describe an internal SKU as a manufacturer part number.

Which identifiers should be submitted?

The correct combination depends on whether official identifiers exist.

For a product with a manufacturer-assigned GTIN:

• Submit the accurate GTIN.
• Submit the correct brand.
• Submit the MPN when applicable and accurately known.
• Do not set identifier_exists to false.

For a product without a manufacturer-assigned GTIN but with a brand and MPN:

• Leave GTIN empty.
• Submit the correct brand.
• Submit the manufacturer-assigned MPN.
• Do not invent a GTIN.

For a genuinely unbranded, handmade, vintage, custom or one-of-a-kind product with no assigned identifiers:

• Leave non-existent GTIN and MPN values empty.
• Set identifier_exists to false when appropriate.
• Do not create artificial identifiers merely to fill the fields.

Google’s missing or incorrect GTIN guidance instructs merchants to provide either an accurate GTIN or, where applicable, both brand and MPN.

What does identifier exists mean?

The identifier_exists attribute tells Google whether applicable unique product identifiers exist for the product.

In Merchant API, this value is represented as a Boolean:

• true
• false

The current Merchant API product attribute reference states that identifierExists should be false when the item does not have appropriate unique product identifiers such as GTIN, MPN and brand. If the value is not provided, it defaults to true.

Setting the value to false is not a general workaround for missing data.

It should be used only when the product genuinely has no assigned identifiers. Google’s identifier exists documentation identifies custom goods, one-of-a-kind products and certain vintage products as possible examples.

Incorrectly setting the value to false can create another warning when Google has evidence that the product should have a recognized identifier.

Products that usually require accurate identifiers

Official identifiers commonly exist for:

• Consumer electronics
• Household appliances
• Branded clothing and footwear
• Packaged food and beverages
• Cosmetics
• Tools
• Toys
• Books
• Vehicle parts
• Office products
• Branded furniture
• Sports equipment
• Replacement components
• Commercial accessories

The absence of an identifier in WooCommerce does not prove that the physical product has no identifier.

It may simply mean that the merchant has not yet recorded the value.

Check the packaging and manufacturer information before deciding that identifiers do not exist.

Products that may genuinely have no GTIN

Some products may not have a manufacturer-assigned GTIN, including:

• Original artwork
• One-of-a-kind handmade products
• Custom-made clothing
• Personalized gifts created by the merchant
• Certain antique products
• Some vintage goods
• Books published before modern ISBN usage
• Unique replacement parts manufactured by the merchant
• Custom furniture
• Bespoke jewellery

Even in these cases, the decision must be made product by product.

A handmade marketplace seller may also resell branded supplies or finished commercial products. Those products should retain their manufacturer-assigned identifiers even if other items in the catalogue are handmade.

Do not set identifier_exists to false across the entire store without reviewing the catalogue.

Store brands and private-label products

A private-label product is made for a business and sold under that business’s brand.

In this situation, the store name or registered private-label name may legitimately be the brand. If the product has an assigned GTIN, submit it. If no GTIN exists, the business may need to use its brand and a suitable manufacturer part number for its own product range.

A merchant that owns the product brand has more control over its internal product identity than a reseller does. However, identifiers should still be:

• Stable
• Unique where required
• Consistent across systems
• Assigned to the correct product
• Assigned to the correct variation
• Preserved during routine updates

Do not change identifiers whenever the product title, price or description changes.

How to handle WooCommerce variations

Variation-level mapping is one of the most common sources of identifier errors.

A variable WooCommerce product may contain separate offers for:

• Size
• Colour
• Material
• Pattern
• Capacity
• Model
• Finish
• Pack quantity
• Compatibility
• Another purchasable option

Each independently submitted variation needs a stable offer ID. It must also use the identifiers belonging to that variation.

For example, a red shoe and a black shoe may have different GTINs even when they belong to the same parent WooCommerce product. Using the parent’s single GTIN for both variations can incorrectly identify one or both offers.

Review the manufacturer’s packaging or catalogue for every variation.

Google’s identifier guidance notes that each variation should use its own accurate GTIN. MPNs may also vary, although some manufacturers use the same MPN for certain apparel sizes.

A reliable variation record should align:

• Offer ID
• SKU
• GTIN
• MPN
• Brand
• Colour
• Size
• Item group ID
• Image
• Price
• Availability
• Landing-page selection

The values should describe one consistent purchasable offer.

For a wider explanation of variation identity, see how to submit WooCommerce variable products to Google Merchant Center.

Do not reuse one GTIN across unrelated products

A GTIN belongs to a specific commercial item.

Do not use one convenient barcode for:

• Every product in a category
• Every variation of a product
• Similar products from different manufacturers
• Different pack quantities
• A replacement product
• A newer model
• A merchant-created bundle
• Products that only share an image
• Products that only share a supplier

A 500 ml product and a 1 litre version may have different GTINs. A single item and a manufacturer-created multipack may also have different identifiers.

Reusing an unrelated GTIN can cause incorrect product matching and Merchant Center identifier issues.

Preserve leading zeros

A GTIN is an identifier rather than an amount used for calculations.

Spreadsheet software, product importers or database processes can accidentally treat it as a number and remove leading zeros. Scientific notation can also corrupt long identifiers.

For example:

0012345678905

must not automatically become:

12345678905

Store GTIN values as text during:

• CSV exports
• CSV imports
• Spreadsheet editing
• WooCommerce migrations
• Bulk product updates
• ERP synchronization
• Database transfers
• API preparation

Also avoid adding spaces, punctuation or descriptive labels to the GTIN field.

Check digit and format errors

A value can have the expected number of digits and still be invalid.

Google can identify problems such as:

• Incorrect check digits
• Invalid lengths
• Unsupported characters
• Truncated leading zeros
• Spaces or hyphens
• ISBN-10 submitted instead of ISBN-13
• A restricted code used inappropriately
• A coupon code submitted as a GTIN
• An internal product number submitted as a GTIN
• One GTIN reused across unrelated products

Do not alter a barcode until it passes validation. Return to the packaging, manufacturer or authorized supplier to obtain the correct value.

Bundles and multipacks need special attention

A bundle combines different products into one offer. A multipack contains multiple identical products sold together.

The correct identifier depends on who created the commercial package.

If the manufacturer created the bundle or multipack and assigned it a GTIN, use the identifier assigned to that complete package.

If the merchant created the bundle, do not use the GTIN of one included item as though it identified the complete bundle. The product data should also communicate that the offer is a merchant-defined bundle.

Similarly, a six-pack should not automatically use the GTIN of one individual unit.

Product identity, title, price, quantity, image, landing page and identifier must all describe the same offer.

Customized products

Customization does not always remove the original product identifiers.

Suppose a merchant engraves a manufacturer-branded watch. The base product may still have a genuine brand, GTIN and MPN. Google’s customized product guidance recommends retaining the identifiers assigned to the product before customization and identifying the offer appropriately as customized.

A completely handmade product created by the merchant may have no external identifiers. A customized version of a recognized commercial product may still retain the base item’s identifiers.

These two situations should not be treated as identical.

Compatible and refurbished products

A compatible product should use the identifiers of the company that actually manufactured the compatible item.

For example, a third-party printer cartridge compatible with an HP printer should not automatically use HP as its product brand. The cartridge manufacturer’s brand and identifiers should be submitted.

A refurbished product normally retains the identity of the original product while its condition is submitted accurately. Do not replace the original manufacturer’s brand with the refurbisher or retailer name unless that description truthfully reflects the product.

Google provides additional rules in its compatible and refurbished third-party product guidance.

Where to store identifiers in WooCommerce

The available fields depend on the WooCommerce version, product configuration and installed extensions.

Identifiers may be stored in:

• A WooCommerce product field
• A variation-level field
• Custom product metadata
• An ERP or inventory integration
• A product import system
• A dedicated barcode extension
• A Merchant integration’s mapping interface

Before entering data, determine which field the authoritative Merchant integration actually reads.

A value visible in the WordPress administration area is not automatically submitted to Google. Likewise, adding an identifier directly in Merchant Center may not correct the WooCommerce source that resubmits the product later.

For every identifier field, confirm:

• Its purpose
• Its storage location
• Whether it belongs to the parent or variation
• Whether the active integration reads it
• Whether imports preserve it
• Whether scheduled updates overwrite it
• Whether it appears in the outgoing product data

A safe correction workflow

1. Identify the affected offer

Open Merchant Center, find the identifier issue and record:

• Offer ID
• Product title
• Data source
• Current GTIN
• Current brand
• Current MPN
• identifier_exists value
• Affected destination
• Issue description

Do not rely only on the title. Several variations may have nearly identical names.

2. Match it to WooCommerce

Locate the exact simple product or variation.

Compare:

• Product ID
• Variation ID
• SKU
• Attributes
• Price
• Availability
• Landing-page URL
• Image

3. Inspect the physical product

Check the barcode and packaging. If the item is not available physically, use official manufacturer or authorized supplier information.

Do not copy identifiers from another retailer without confirming that the product, model, variation and pack quantity are identical.

4. Classify the product

Determine whether it is:

• A branded mass-produced product
• A private-label product
• A handmade product
• A customized commercial product
• A vintage product
• A bundle
• A multipack
• A compatible product
• A refurbished product
• A variation

This classification determines which identifiers should exist.

5. Correct the authoritative source

Update the correct WooCommerce product, variation or connected inventory source.

Do not correct only a temporary output when the next synchronization will restore the old value.

6. Review the identifier combination

Confirm that:

• GTIN belongs to the exact item.
• Brand identifies the correct manufacturer or private label.
• MPN belongs to the same brand and product.
• identifier_exists is not falsely set to false.
• Variation identifiers are not inherited incorrectly.
• Leading zeros remain intact.

7. Resynchronize the product

Use the source responsible for ongoing Merchant Center product management.

Avoid submitting the same correction through several competing integrations.

8. Allow processing time

A successful Merchant API request means the operation was accepted for processing. It does not prove that the product has completed evaluation or that every issue has already been cleared.

9. Verify the result

Search by offer ID and confirm that:

• The corrected values are visible.
• The product belongs to the intended source.
• No other variation was changed.
• The identifier warning or disapproval is removed.
• The old values do not return during the next scheduled synchronization.

How PW Merchant API fits into identifier management

PW Merchant API is designed to help organize supported WooCommerce and Google Merchant API product operations.

WooCommerce remains the commercial source of product information. PW Merchant API can read supported WooCommerce data and communicate supported product operations to Google Merchant Center through Merchant API.

Depending on the supported fields and installed version, this workflow can help users:

• Review WooCommerce product information
• Work with simple and variable products
• Prepare supported product attributes
• Submit new products
• Update existing product records
• Organize scheduled workloads
• Review successful and unsuccessful operations
• Identify products requiring correction

The presence of an identifier field does not prove that its value is correct. PW Merchant API cannot determine with certainty whether a number printed by a supplier is genuinely assigned to the product.

It also cannot:

• Invent valid manufacturer identifiers
• Guarantee Merchant Center approval
• Change Google’s product data requirements
• Correct inaccurate manufacturer information
• Force Google to process a correction immediately
• Control identifiers supplied by another data source
• Guarantee impressions, clicks, rankings or sales

A WooCommerce Google Merchant Center plugin can organize the communication process. The merchant remains responsible for the accuracy of the source product information, while Google independently processes and evaluates the submitted data.

Common identifier mistakes

Using an SKU as a GTIN

An internal WooCommerce SKU is not a global trade identifier.

Inventing a barcode

A random number that has the correct length is not a legitimate GTIN.

Using the supplier as the brand

The supplier may distribute the product without manufacturing or branding it.

Using the store name for every product

The store name is appropriate only when the merchant genuinely owns or manufactures the relevant brand.

Setting identifier exists to false for the entire catalogue

Most branded mass-produced products have assigned identifiers.

Using one GTIN for every variation

Different colours, capacities, models or pack quantities can have different identities.

Removing leading zeros

This changes the identifier.

Correcting only Merchant Center

The incorrect value may return when WooCommerce or another source synchronizes again.

Copying an identifier from a similar product

A visually similar product may have a different manufacturer, model, variation or pack quantity.

Adding brand text to the MPN

The MPN field should contain the manufacturer’s part number rather than a rewritten promotional label.

Deleting and recreating products unnecessarily

This can change local IDs and offer relationships without fixing the underlying identifier source.

Frequently asked questions

Is a WooCommerce SKU the same as a GTIN?

No. A WooCommerce SKU is normally an internal stock reference. A GTIN is a standardized identifier assigned to a commercial product.

Can I use an SKU as an MPN?

Only when the value is genuinely the part number assigned by the manufacturer. Do not describe an internally created SKU as an MPN without evidence.

Where can I find a GTIN?

Check the barcode on the product or packaging, the book cover, official manufacturer documentation or information supplied by an authorized distributor.

Can I create my own GTIN?

A reseller should not invent a GTIN. Businesses that need to assign official identifiers to products they manufacture should follow the appropriate GS1 process for their market.

Does every product have a GTIN?

No. Handmade, one-of-a-kind, custom and certain vintage products may not have manufacturer-assigned GTINs.

What should I submit when a product has no GTIN?

When available, submit its accurate brand and manufacturer-assigned MPN. If no applicable unique identifiers genuinely exist, use the appropriate identifier_exists configuration.

Should I write “N/A” in an empty GTIN field?

No. Leave a non-existent identifier empty and use the appropriate identifier configuration. “N/A” is not a valid GTIN.

Can I copy a GTIN from another online store?

Do not rely on another retailer’s listing alone. Confirm the identifier using the product, packaging, manufacturer or authorized documentation.

Should every WooCommerce variation have a different GTIN?

Each variation should use the GTIN assigned to that exact item. Many variations have different GTINs, but the manufacturer’s official information is authoritative.

Can two size variations share the same MPN?

They can when the manufacturer uses the same MPN for those sizes. Do not assume this; verify the manufacturer’s system.

What brand should a compatible accessory use?

Use the brand of the company that manufactured the compatible accessory, not automatically the brand of the product with which it is compatible.

What brand should I use for a private-label product?

Use the private-label brand under which the product is genuinely manufactured and sold.

Should a refurbished product use the refurbisher as its brand?

Normally, the original product manufacturer remains the brand. Submit the product’s condition accurately and follow Google’s applicable refurbished-product requirements.

Why does Google say my product has an identifier when I set identifier exists to false?

Google may have evidence from equivalent offers that the product has a manufacturer-assigned GTIN or other identifiers. Check the physical product and official manufacturer data.

How long will the identifier correction take?

Processing is not always immediate. Allow Merchant Center time to receive, process and evaluate the updated data before repeatedly resubmitting it.

Can PW Merchant API verify that a GTIN is genuine?

It can communicate supported product values, but it cannot establish manufacturer ownership or guarantee that an identifier genuinely belongs to the product.

Do accurate identifiers guarantee Google Shopping visibility?

No. Accurate identifiers improve product-data quality, but Google independently determines eligibility, placement and visibility.

Final checklist

Before considering a GTIN, brand or MPN issue resolved, confirm that:

• The affected Merchant Center offer was identified by offer ID.
• The exact WooCommerce product or variation was found.
• The authoritative data source is known.
• The physical product or official manufacturer information was checked.
• The GTIN belongs to the exact product and variation.
• Leading zeros were preserved.
• No spaces, hyphens or labels were added to the GTIN.
• The brand identifies the correct manufacturer or private label.
• The MPN was assigned by the manufacturer.
• An internal SKU was not misrepresented as a GTIN or MPN.
• One GTIN was not reused across unrelated products.
• Variation identifiers match variation attributes.
• Bundle and multipack identities were reviewed correctly.
• Customized products retained applicable base-product identifiers.
• identifier_exists is false only when identifiers genuinely do not exist.
• The correction was made in the source that controls future updates.
• The product was resynchronized through the authoritative workflow.
• Merchant Center was allowed time to process the change.
• The issue was checked again using the same offer ID.
• Scheduled updates do not restore the incorrect values.

Missing GTIN, brand and MPN issues should be treated as product-identity problems rather than empty-field problems.

The safest process begins with the physical product and its manufacturer information. WooCommerce should store the correct commercial data, the active integration should communicate supported fields accurately and Google Merchant Center should independently process and evaluate the submitted offer.

When identifiers are genuine, stable and mapped to the correct product variations, WooCommerce product management becomes easier to trace and Merchant Center identifier problems become easier to diagnose, correct and prevent.