When customers cannot complete a purchase.
FIRST, REPRODUCE IT
Buy something yourself, as a guest, on a phone. Many checkout faults appear only when logged out or on mobile.
COMMON CAUSES
No shipping zone covering the customer's address, so checkout will not proceed for physical goods A payment gateway misconfigured or in test mode while live A plugin conflict, particularly with page builders and custom checkout fields Caching applied to the checkout page A theme not updated for the current WooCommerce version PHP memory exhausted during checkout
DIAGNOSING
Enable WP_DEBUG logging and reproduce the error, then read wp-content/debug.log Check cPanel > Metrics > Errors for the same period Deactivate plugins one at a time, testing checkout after each, starting with anything that touches checkout Switch temporarily to a default theme to rule the theme out
IF IT IS INTERMITTENT
Check resource usage. Checkout failing at peak times points to hitting a plan limit rather than a code fault.
FIX IT IMMEDIATELY
A broken checkout costs every sale until resolved.
