A WooCommerce Store API checkout error is easy to miss because the checkout page can still render. The real break often appears only when cart state, shipping rates, payment methods or block validation are refreshed through Store API calls.
The useful diagnosis is not "the site is down". It is whether Store API returns consistent cart data, whether checkout blocks hydrate correctly, whether payment methods are removed after a shipping or country change, and whether the final state reaches order confirmation.
Evidence should answer these questions:
- Does Store API return a valid cart before checkout? - Do shipping, coupon and address changes keep the same cart state? - Are payment methods present before and after block hydration? - Does the checkout fail with a REST error, timeout or malformed response? - Is the buyer blocked before any order is created?
CashFlowCanary treats Store API checkout errors as conversion incidents when a controlled journey reaches the WooCommerce checkout but the API state prevents a usable final path. Reports keep technical status, step names and response classes only; buyer identity, payment data and precise cart contents stay out of the proof. Start with features, compare plans, or request a free audit.
This guide complements WooCommerce Checkout Blocks broken, WooCommerce checkout timeout, WooCommerce checkout validation error and WooCommerce no payment methods available. Together they separate Store API failures from block rendering, slow responses, validation and missing payment gateways.