What Breaks WooCommerce Checkout (and How to Fix Each Issue)

WooCommerce checkout breaks for predictable reasons. The same six or seven patterns account for the overwhelming majority of “my checkout stopped working” tickets. This guide walks through each, with the symptom you see, the underlying cause, and the specific fix.

1. Payment Gateway Plugin Update Broke the Checkout JavaScript

Symptom: Customer fills in card details, clicks “Place Order,” nothing happens. Or the page refreshes and the cart is empty. Or the order shows up in WooCommerce admin as “pending payment” forever.

Cause: Payment gateway plugins (Stripe, PayPal, Square, etc.) ship updates that change the checkout JavaScript. If the cached version of the page on the user’s browser, or on your caching layer, doesn’t match the new plugin version, the checkout silently fails.

Fix:

1. Clear all caches: WordPress page cache, browser cache, CDN cache.
2. Open the checkout page in an incognito window and check the browser console (F12 → Console tab) for JavaScript errors.
3. If errors reference the payment gateway plugin, roll back to the previous plugin version (available on WordPress.org → plugin page → Advanced View → Previous Versions).
4. Report the issue to the plugin author with the error text.

2. Conflict Between Payment Gateway and Page Builder

Symptom: The checkout page loads but the payment fields don’t appear, or they appear but accept input that doesn’t get submitted.

Cause: Page builders (Elementor, Divi, WPBakery) often override how WooCommerce renders the checkout. If the page builder’s checkout block was created with one version of the payment gateway, a gateway update can break the override.

Fix:

1. Switch the checkout page from the page builder layout to the default WooCommerce checkout shortcode (
   ).
2. Test the checkout. If it works, the page builder layout is the issue.
3. Rebuild the page builder layout against the current gateway version, or accept the default checkout layout (which is usually fine and faster anyway).

3. Shipping Zones Don’t Match Customer Location

Symptom: Customer in a valid shipping region sees “No shipping methods have been found” at checkout.

Cause: Shipping zones in WooCommerce are matched by exact country/state/postal code patterns. A misconfigured zone (typo in the postal code range, missing state, country code mismatch) means valid customer addresses don’t match any zone.

Fix:

1. WooCommerce → Settings → Shipping → Shipping Zones.
2. Click into each zone and verify the locations actually cover where your customers are.
3. Check if there’s a “Locations not covered by your other zones” zone — if it exists with no shipping methods, customers outside your defined zones see the error.
4. For complex setups, install Shipping Zone Validator (or similar) to test specific addresses.

4. SSL Certificate Issue on Checkout Specifically

Symptom: Checkout shows mixed content warnings, payment gateway refuses to load, or the browser blocks the page entirely with a security warning.

Cause: SSL covers the site but something in the checkout page is loaded over HTTP (an image, a script, a font). Payment gateway plugins refuse to operate on mixed-content pages.

Fix:

1. Open the checkout page in Chrome, view the console (F12 → Console).
2. Look for “Mixed Content” or “blocked:mixed-content” errors. The error names the specific resource.
3. Update the resource URL to HTTPS, or use a plugin like Really Simple SSL to force HTTPS sitewide.
4. Clear all caches after the fix.

5. Email Order Confirmations Aren’t Sending

Symptom: Orders process correctly. Customers don’t receive order confirmation emails. They email asking if the order went through.

Cause: WordPress sends mail via PHP’s mail() function by default, which most hosts have effectively disabled or which gets routed to spam. Order emails are sent the same way as any other WordPress email.

Fix:

1. Install an SMTP plugin: WP Mail SMTP, FluentSMTP, or Post SMTP.
2. Configure it with a real email service (Mailgun, SendGrid, Brevo, or a transactional service from your existing email provider).
3. Send a test email through the plugin to confirm delivery.
4. Place a test WooCommerce order and confirm the order confirmation arrives.

This isn’t really a checkout-breaking issue — orders complete — but the customer experience suggests checkout is broken, and that’s what generates support tickets.

6. Cart Calculation Errors (Discount Codes, Taxes)

Symptom: Customer applies a coupon code and sees an error, or the total doesn’t match what the customer expects, or tax isn’t calculating correctly.

Cause: Coupon plugins (Smart Coupons, Advanced Coupons) intercept WooCommerce’s cart calculation. A plugin update or configuration change can break the calculation hook.

Fix:

1. Deactivate the coupon plugin. Test if standard WooCommerce coupons work.
2. If standard coupons work, the third-party plugin is the issue — check for updates or reconfigure the rules.
3. For tax issues: WooCommerce → Settings → Tax. Confirm the tax rates are entered correctly for the customer’s location, and the “Calculate tax based on” setting matches your business reality (shop base, customer billing, or customer shipping).

7. Sessions / Cart Not Persisting

Symptom: Customer adds items to cart, navigates to checkout, cart is empty.

Cause: Caching configuration is caching the cart page or checkout page, serving the same cached version to all users (without their cart contents). This is a configuration error in the caching plugin.

Fix:

1. In the caching plugin settings, add /cart/, /checkout/, /my-account/ (and their localized equivalents) to the “Never Cache” or “Excluded URLs” list.
2. Some plugins also need cookies excluded — add woocommerce_cart_hash, woocommerce_items_in_cart, wp_woocommerce_session_* to the excluded cookies list.
3. Clear all caches and test.

8. Plugin Conflict Causes Checkout to Throw a 500 Error

Symptom: Checkout page shows a “500 Internal Server Error” or a white screen.

Cause: A plugin is throwing a PHP fatal error specifically on the checkout page. The error log will show the specific plugin and line.

Fix:

1. Check the server error log (most hosts expose this; or check /wp-content/debug.log if WP_DEBUG_LOG is enabled in wp-config.php).
2. The log entry names the specific plugin file. Deactivate that plugin.
3. Test the checkout. If it works, the plugin is the issue — either update it, replace it, or find the configuration that triggered the conflict.

For systematic plugin conflict diagnosis, see WordPress Plugin Conflict Diagnosis.

What to Do When You Can’t Identify the Cause

If the symptoms don’t match the above, or if you’ve tried the obvious fixes and the checkout is still broken on a live revenue-generating store, the cost-benefit math shifts. Every hour of broken checkout is real lost revenue plus the opportunity cost of your time.

Synergetic’s Emergency WordPress Diagnostic is the productized fix path: fixed price, engineer triage within 24 hours, scope confirmed before any further work. It’s specifically built for “the site or store just broke and I need someone competent looking at it now” — not for the chronic slow-burning issues, which are better suited to a care plan or a technical SEO review.

For preventing the failures above from happening in the first place, the WordPress maintenance for WooCommerce guide covers what a WooCommerce-aware care plan actually tests after each update. For deeper conversion-optimization work (not just keeping the checkout working but making it convert better), see WooCommerce Checkout Optimization.