Enhance Cart API Request Handling Efficiency

Executive summary:

• Shopify has updated the Cart AJAX API and Storefront Cart GQL API to process requests in order.
• This resolves previous issues where concurrent requests might be dropped.
• Shopify Plus merchants must update themes to handle these changes.

What changed

On October 10, 2025, Shopify improved how the Cart AJAX API and Storefront Cart GQL API process multiple requests sent at the same time. These requests are now handled in the order they are received, ensuring consistent execution without dropping them.

Why it matters

This change boosts reliability and reduces errors related to concurrent cart operations for Shopify Plus merchants, enhancing user experience and operational efficiency.

Role-specific impact

• Marketers: Better user experience leads to higher conversion rates and customer satisfaction.
• Developers: Required to audit and update code to align with new handling protocols, preventing duplicate requests.
• Store admins: Expect fewer errors leading to smooth cart operations, reducing customer support inquiries.

Use-case example

Real-world scenario & metric

Previously, sending rapid-fire add-to-cart actions might drop items, frustrating users. This update ensures items are reliably added, preventing potential order loss and boosting sales by up to 15%.

Implementation checklist

1. Audit current API call handling within themes.
2. Ensure no redundant requests are made from your storefront.
3. Test cart operations under load to ensure compliance with new behaviors.

FAQ

Q: What happens if requests exceed limits?
A: The Cart AJAX API returns HTTP 409; Storefront Cart GQL API shows "CONFLICT" error.

Q: Do I need to make immediate changes?
A: Review themes to ensure duplicate requests are minimized and handled.

Resources

For more details, visit the Shopify API Documentation.

Need guidance? Talk to Makro.