WooCommerce checkout not working? Find the fault in this order

First: reproduce it like a customer

Open a private browser window, put a product in the cart and go through the checkout yourself — on your phone as well. Note exactly where it stops: does the payment window never open, does the card get declined, does the page reload with no message, or does the order hang as "pending"?

Where it stops points to the cause. A payment window that never opens is usually a script conflict on the page. An order stuck in "pending payment" usually means the payment provider answered but your site never received the confirmation.

The payment gateway and its keys

Vipps, Klarna, Stripe and card gateways all authenticate with keys, and the keys expire, get rotated or point at test mode. In WooCommerce, open the payment method settings and confirm live mode and live keys. Then check the gateway dashboard for failed webhook deliveries — that is the channel that flips orders from pending to paid.

If the gateway logs show webhooks failing, the usual suspects are a security plugin blocking the callback URL or an SSL problem on the site.

Plugin conflicts and caching

The checkout is the most JavaScript-heavy page of the shop, so it is where plugin conflicts surface first — often right after an update. If the fault appeared after updating, that update is your prime suspect.

Caching is the other classic: a cached checkout page can serve one customer another customer’s session, or an outdated security token that makes every payment fail. The checkout, cart and account pages must be excluded from full-page caching, and that exclusion must be verified — not assumed.

When to hand it over

If the checks above do not isolate the fault, the debugging moves into logs, the database and the payment provider’s API — territory where trial and error on a live shop costs real orders. That is a fix we do often, and it is usually a technical support job of hours, not days.