The WooCommerce plugin conflicts we see on 70% of new intake stores

We run an access audit on every new client before we touch anything. Across the last 80-odd audits, we’ve seen the same five conflicts appear again and again — independently, on stores of every size. Here they are, ranked by frequency.

1. Multiple caching plugins active simultaneously

W3 Total Cache + WP Super Cache + the hosting provider’s built-in cache is a common combination. Each one has different rules for when to invalidate cache, and they conflict constantly. Symptoms: cart contents persisting between sessions, prices not updating, logged-in / logged-out state bleeding over.

Fix: pick one caching layer, configure it properly, disable the rest.

2. Payment gateway SSL certificate mismatch

The store’s SSL certificate is issued to www.example.com but the gateway callback URL is configured to example.com (without www), or vice versa. The gateway POSTs to the wrong URL, gets a redirect, drops the POST body, and the order stays in pending. Checkout “works” but orders don’t complete.

Fix: ensure the callback URL in the payment gateway portal exactly matches the store URL in WordPress settings.

3. WooCommerce session handler conflicts with object caching

WooCommerce stores sessions in the database by default. When object caching (Redis, Memcached) is added, some configurations start caching session data without proper invalidation. Result: cart totals are stale, coupons don’t clear properly, checkout state is inconsistent.

Fix: configure WooCommerce to use its own session handler explicitly and exclude session keys from the object cache.

4. Page builder CSS interfering with checkout

Elementor, Divi, and Beaver Builder all inject global CSS. Their reset styles and grid systems frequently break WooCommerce checkout step layouts — particularly the order review column, payment method selection, and the place order button on mobile.

Fix: audit checkout pages for page builder CSS interference; usually solvable with targeted overrides scoped to woocommerce-checkout class.

5. Duplicate order bump / upsell plugins

Two different upsell plugins both hooking into woocommerce_add_to_cart and woocommerce_checkout_order_processed. Symptoms: duplicate line items, incorrect totals, failed webhook signatures because the order data is different from what was authorized.