A Gateway Plugin Broke My WooCommerce Checkout
Why Guessing Doesn't Work
Checkout page errors caused by a plugin conflict usually stem from either a JavaScript error (one script breaking execution for scripts loaded after it) or a PHP-level hook conflict (two plugins modifying the same checkout behavior in incompatible ways). Both can produce symptoms that look identical to a gateway-specific bug, and there's no way to identify the actual culprit from the symptom alone — systematic isolation is the only reliable method.
The WooCommerce Isolation Process
- Always do this on a staging copy, never on the live site, since deactivating plugins can itself disrupt real customers mid-checkout.
- Switch to a default WordPress theme (like the current Twenty* theme) temporarily, since a custom theme's checkout template overrides are a common, easily overlooked conflict source.
- Deactivate every plugin except WooCommerce and the payment gateway plugin itself, then confirm checkout genuinely works in that minimal baseline state before reactivating anything.
- Reactivate plugins one at a time, testing checkout fully after each reactivation, rather than reactivating several at once and losing the ability to isolate which one caused the regression.
Once the Conflicting Plugin Is Found
- Check the conflicting plugin's changelog and support forum for any known compatibility issue with the specific gateway plugin in use — this may already have a documented fix or a compatibility setting.
- Update both plugins to their latest versions if not already current, since compatibility issues between actively maintained plugins are often addressed over time.
- If no fix exists, a targeted code fix (adjusting hook priority, or conditionally disabling the conflicting behavior at checkout specifically) is usually possible without losing the conflicting plugin's functionality elsewhere on the site.
Need help isolating and fixing a specific checkout conflict? See WooCommerce fixes.