GA4 transaction_id does not match the Shopify order

GA4 receives purchases, but their transaction_id is not the Shopify order id, number or name.

Why it matters

Without a stable order identifier, GA4 cannot deduplicate purchases and no tool can reconcile GA4 with Shopify order by order.

How to fix it

1. In GA4, open Reports → Monetization → Ecommerce purchases and add the Transaction ID dimension to see what is being sent.
2. Set transaction_id to the Shopify order id or order name (for example #1001) in your purchase event; the Google & YouTube app does this by default.
3. If you use Google Tag Manager, map transaction_id from the checkout_completed event’s order id, not from a random or session value.
4. Remove any second integration sending purchases with a different id, then allow 24–48 hours for GA4 data to settle.

Background reading

• Shopify orders don’t match GA4: how to find the exact missing orders
• GA4 shows more purchases than Shopify: how to find duplicate purchase events

After a fix, TagGap confirms it on the next comparison run. Questions: support@taggap.com.