The `cartDiscountCodeUpdate` mutation now requires the `discountCodes` field

[Jonas]

I was able to resolve the issue by adding a storefront access token to the request.

[Storefront API] cartCreate raise error

Did you try to add a Storefront-Access-Token to the request? const response = await fetch(`https://${shop}/api/2025-07/graphql.json`, { method: 'POST', headers: { 'Content-Type': 'application/json', 'X-Shopify-Storefront-Access-Token': window.themeVariables.settings.storefrontToken, }, body: JSON.stringify({ query: mutation, variables }), });