Although many of my products have UPC’s (Barcodes), i still get a error in Sales channels → google → Approved. It says “! You need to add a gtin or mpn”.
Is there a column header i can use to upload Google MPN’s in bulk?
You may consider using: https://apps.shopify.com/bulk-product-editor?surface_detail=albastar&surface_inter_position=1&surface_intra_position=1&surface_type=search
However, first check Google Merchant Center > Products > All Products > click on a product > scroll to the bottom and view the final attributes.
Do you see your barcodes listed? If not and you have added them in Shopify, then the app you are using is bugged, and you need to contact Shopify support.
If this is your issue, you are not alone, it’s a known issue for more than a year now. And to fix this for my clients I use: https://apps.shopify.com/multiple-google-shopping-feeds