Cart is getting empty when user visits checkout page from external website using multipass auth.

Topic summary

Cart items are being cleared on Shopify when a user returns to checkout from an external headless site using Multipass single sign-on after a previous, incomplete checkout visit. The first redirect to Shopify checkout works; subsequent attempts show an empty cart.

Setup: Headless implementation via Shopify Storefront GraphQL API. Users are redirected to Shopify’s checkout with a Multipass token and can complete payment successfully on first attempt.

Key observation: Shopify’s checkout sets cookies; if the cart-related cookie is deleted before redirecting to checkout, the cart does not get emptied. This suggests a cookie or session interaction with Multipass is resetting the cart on subsequent visits.

Status: No documentation or known issues found. Seeking guidance; issue remains unresolved. Temporary workaround: clear the cart cookie before redirecting to checkout.

Summarized with AI on January 10. AI used: gpt-5.

We have integrated Shopify’s headless e-commerce using its storefront graphQL APIs. When a user purchases any product on our site, we update that info to Shopify. When the user clicks the checkout button on our site, we redirect the user to Shopify’s checkout page using a multipass token and end-point. Redirection works fine and the user can submit card details and able to complete the purchase.

So far everything works fine but when the user comes back to our site without purchase and again tries to go to Shopify’s checkout page, the cart is getting cleared/empty on Shopify’s end. Looks like multipass authentication is affecting the cart and it only works for the very first time.

One thing I observed it, on Shopify’s checkout page some cookies are getting created and if I delete the cart cookie manually before the user visits the checkout page, the cart is not getting empty. Not able to find any docs or issues related to this. Can anyone please help me with this?

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