Shopify "Add to Cart" button not working
Quick answer
When the add-to-cart button does nothing, a JavaScript error is almost always blocking it — usually from a recent theme edit, an app script, or a conflict between two apps. Open the browser console on a product page, read the first red error, and disable or revert whatever it points to. This breaks the funnel before checkout, so orders can drop to near zero.
Symptoms
- Clicking "Add to cart" does nothing or throws an error
- The cart never updates or always shows empty
- Product page looks fine but the funnel produces no orders
Common causes
- A theme customization introduced a JavaScript error
- An app (upsell, bundle, sticky cart) script conflicts with the theme
- A duplicate jQuery/script load from an app breaks event handlers
How to check
- 1.Open the browser console on a product page and read the first red error
- 2.Disable recently added apps one at a time and re-test
- 3.Try the default Shopify theme temporarily to confirm it's theme vs. app
How to fix it
1. Read the console error
The first red error usually names the script or app breaking the button. That's your culprit.
2. Revert the last theme edit
If you edited the theme recently, roll back to the previous version from your theme library.
3. Disable conflicting apps
Turn off recently added cart/upsell apps one at a time until the button works.
4. Monitor the full journey
Add-to-cart breaks are invisible in uptime tools — the site is "up". Journey monitoring that clicks through add-to-cart catches it.
How Liulum helps
Liulum watches this path continuously and alerts you in plain English the moment it breaks — catching a silent failure in under a minute instead of hours from a customer complaint. Think of it as insurance for the checkout that makes you money.
Protect your storeFrequently asked questions
Why is my add to cart button not working on Shopify?
A JavaScript error is blocking the click handler, almost always from a recent theme change or an app script conflict. The browser console will point you to the exact source.
Why don't uptime monitors catch this?
Uptime tools only check that the page loads (HTTP 200). The page is up — the button is broken. You need journey monitoring that actually exercises add-to-cart and checkout to catch functional breaks.
How does Liulum catch add-to-cart failures?
Liulum's revenue-journey monitoring tests the real path from product page to checkout, so a broken add-to-cart button is caught and reported even though the store is technically "up".