Shopify checkout error after theme update: what to do

Problem

After updating your theme, checkout buttons may redirect incorrectly, payment options disappear, or customers see a generic checkout error.

Solution

• Rollback / compare theme versions and re-apply changes using theme diff (most issues come from overwritten snippets/sections).
• Check for broken cart/checkout related snippets (cart items, cart form, cart attributes).
• Re-test payment gateways and shipping rates (apps sometimes inject scripts that stop working after updates).
• Use Shopify’s theme inspector / browser console to locate JavaScript errors tied to cart submit or drawer logic.

Quick checklist

• Duplicate theme before changes
• Compare snippets and sections
• Test gateway + shipping
• Check console errors