Shopify checkout not working — how to diagnose and fix it
Quick answer
A Shopify checkout usually fails for one of four reasons: a recently installed or updated app injecting a script error, a payment gateway in test mode or misconfigured, a broken discount/shipping rule, or a third-party service (pixel, review app, chat widget) throwing a JavaScript error that blocks the checkout button. The fastest fix is to identify the last change made to the store, revert it, and place a real test order to confirm.
Symptoms
- Customers reach checkout but the "Pay now" button does nothing or spins forever
- Orders suddenly drop to zero while traffic stays normal
- Customers email or DM that they "can't pay" or "the page froze"
- Abandoned-checkout count spikes at the payment step specifically
Common causes
- A newly installed or auto-updated app injected a script that errors on the checkout page
- Payment gateway switched to test mode, expired credentials, or a failed provider integration
- A discount, tax, or shipping rule that produces an invalid total for some carts
- A third-party tag (Meta Pixel, TikTok, reviews, chat) throwing a JS error that halts checkout
How to check
- 1.Place a real test order end-to-end from an incognito window on mobile and desktop
- 2.Check Shopify Admin → Settings → Payments that your provider is live, not test
- 3.Open the browser console on the checkout page and look for red JavaScript errors
- 4.Review Shopify Admin → Apps for anything installed/updated right before orders stopped
How to fix it
1. Find the last change
Check your app list, theme edits, and payment settings for anything changed in the 24-48h before orders stopped. The cause is almost always the most recent change.
2. Roll it back
Uninstall or disable the suspect app, or revert the theme change, then place a test order. If checkout works, you found it.
3. Verify the gateway
Confirm your payment provider is live and credentials are valid. Run one real low-value order to confirm money actually moves.
4. Re-test every path
Test with a discount code, with different shipping regions, and on mobile — many checkout breaks only affect one path.
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 did my Shopify checkout stop working suddenly?
The most common trigger is a change you or an app made recently — an app update, a new script, or a payment or discount setting. Shopify itself rarely breaks; the change is usually on your store. Identify and revert the last change first.
How do I know if I'm losing sales to a broken checkout?
Watch for a sudden drop in orders while traffic and add-to-carts stay normal, or a spike in abandoned checkouts at the payment step. Continuous checkout monitoring catches this within a minute instead of hours later from a customer complaint.
Can Liulum fix my Shopify checkout automatically?
On Shopify, Liulum watches your checkout continuously and alerts you the moment it breaks — with a plain-English diagnosis of what changed. Shopify runs the infrastructure, so the fix (reverting the app/setting) is applied by you or your developer; Liulum makes sure you know in seconds, not hours.