The final step fails.
WHAT IT COSTS
Every minute this is broken is lost revenue, and customers rarely report it.
FIRST
Check cPanel > Metrics > Errors for a fatal error at the time.
Check the browser console for JavaScript errors, which frequently prevent checkout rendering.
THE COMMON CAUSES
A plugin conflict, particularly checkout customisations and page builders A JavaScript error stopping the form rendering The checkout page missing its required shortcode or block Caching serving a broken cached version A payment plugin failing
CHECKING THE PAGE ITSELF
WooCommerce > Settings > Advanced confirms which page is set as checkout.
Open that page and confirm it contains the checkout shortcode or block. A page builder can strip it.
ISOLATING
Disable plugins in groups, testing after each.
Switch to a default theme temporarily.
CACHING
Purge everything, and confirm checkout is excluded from caching.
THE HABIT
Buy something from your own shop weekly, as a guest, on a phone.