How do I keep my custom code when updating?

Custom code is the #1 reason updates become painful. The goal is to keep edits small and isolated.

Best practices that reduce pain

• Prefer theme settings/blocks over code edits.
• Put CSS changes in a dedicated custom CSS area/file when possible.
• Avoid editing core files unless necessary.
• Document every change (file, reason, date).

Recommended merge approach

1. Identify your custom changes (diff).
2. Apply them to the updated theme deliberately.
3. Retest affected areas only (don't "spray and pray").

When to ask a developer

If your store relies on heavy Liquid changes or complex app integrations, a developer-assisted merge is worth it.

Related articles

• How do I update the theme safely?
• Where should I put custom CSS?
• Browse all FAQs