Shopify variant GTIN and MPN issues in Merchant Center

Where variant issues hide

• Only the first variant has a barcode.
• Some variants have SKU values, but no real GTIN or MPN.
• Variant titles do not include size, color, or material in a way Google can interpret.
• Variant item IDs changed after app migration or CSV import.
• Google receives duplicate identifiers across different variants.

Diagnosis checklist

• Export all product variants from Shopify.
• Group by product handle and count variant rows.
• Filter blank barcode, blank SKU, blank option values, and duplicate barcode values.
• Compare affected variant IDs with Merchant Center item IDs.
• Check whether the issue applies to every variant or only certain options.

Fix strategy

Do not fix one disapproved variant at a time unless only one variant is affected. Most variant issues are pattern issues. Fix the source fields, then confirm the app or feed maps the corrected data to Merchant Center.