The Call
It was 9pm the night before Black Friday. A client's WooCommerce store had been processing orders normally all day, and then it stopped. No error message on the checkout page. Just silent failure — the customer would fill out their card information, click submit, and nothing would happen. No confirmation, no error, no charge.
The Diagnosis
The client had run a routine plugin update that afternoon. One of the plugins — a seemingly unrelated popup tool — had a JavaScript conflict with the payment gateway's checkout scripts. The scripts were interfering with each other on the payment step, and the browser was swallowing the error silently.
Diagnosing this took about 45 minutes of console log inspection, plugin deactivation testing, and reviewing the update changelog. The conflict was in a three-line JavaScript block that the popup plugin was injecting unconditionally on every page.
The Fix
We deactivated the plugin, confirmed checkout was working, then added a conditional to the plugin's JavaScript injection so it wouldn't fire on WooCommerce checkout pages. Tested across three browsers and two devices. Total time: two hours from first diagnosis to confirmed resolution.
Black Friday Traffic Hit Normally
The store processed its highest single-day revenue ever the next day. The fix cost $175. The alternative would have been a full day of missed sales on their highest-traffic day of the year.
This is exactly what the Quick Fix is for. One problem. One price. Done before it costs you more than you're paying to fix it.