The barcode column contains something that is not a valid GTIN, or the same barcode appears twice in the store.
Validate barcodes at the source. One wrong check digit fails the whole row.
The free Shopify CSV checker names the exact line for each problem. The paid Rescue Kit adds 20 more error cases, a template in Shopify's column order, and the same checker as a script for your pipeline.
See the Rescue Kit →