You should only have 1 feed app per channel. So for Google Shopping, only use 1 app. This to avoid conflicts, and policy violations.
Topic summary
Google Merchant Center is flagging “Missing value [GTIN]” for products synced via Shopify’s Google Channel app. Manual GTIN/UPC entries in Merchant Center don’t persist because the Shopify app overwrites data daily; updates must be made in Shopify’s Barcode field. GTIN (Global Trade Item Number) includes UPCs.
Key points and guidance:
- Enter valid barcodes in Shopify; do not invent codes to avoid disapproval.
- The default Shopify Google app is reported as buggy; multiple users saw issues persisting for months.
- Alternatives: use a third‑party feed app (e.g., Multiple Google Shopping Feeds, others with free trials) or upload a supplemental feed (spreadsheet with id, brand, barcode) per Google’s guide.
- Only one feed app per channel should be active to avoid conflicts.
- For custom products, confusion persists: GMC may show “GTIN Needed” yet “GTIN isn’t needed for custom.” “Custom product” is a Shopify attribute, not a GMC field; setup must be done in the feed app per provided video/docs (identifier handling is configured there).
Updates/outcomes:
- One user reports the issue is now resolved after applying suggestions (no method detailed).
- Another user installed a third‑party app and is following setup guides.
Status: Partially resolved; root cause likely Shopify app sync bug. Some open questions remain (exact successful steps not shared). Screenshots and video guides were provided.