Shopify Scripts to Functions Migration: Complete Guide (June 2026 Deadline)

TL;DR

• Shopify Scripts deprecated — must migrate to Functions by June 2026
• Functions execute faster and have better parity with Shopify's backend
• Migration is not automatic — requires code rewrite from Ruby to JavaScript/TypeScript
• New API capabilities in Functions that Scripts couldn't access
• Start now — June deadline is closer than it looks

The Deadline: June 2026

Shopify announced in Winter '26 Edition that Scripts will be fully deprecated by June 2026. After that date, Script-based checkout customizations will stop working.

Scripts vs Functions: Key Differences

Functions now run on WebAssembly (edge, sub-5ms execution) vs Scripts running on Shopify's legacy infrastructure. Functions use JavaScript/TypeScript instead of Ruby, and have access to the full GraphQL Admin API with AI integration capabilities.

Migration Strategy

1. Inventory your Scripts — Find all Scripts in store using Shopify CLI or Admin.

2. Choose Function Type — Product discounts, order discounts, shipping discounts, payment customizations, or delivery customizations.

3. Rewrite Logic — Convert Ruby → TypeScript. Key change: direct mutation becomes return output object.

Common Migration Challenges

Metafield Access: Scripts could read metafields directly. Functions require GraphQL input queries.
External API Calls: Neither Scripts nor Functions support this (WebAssembly sandbox). Use Shopify Flow + app backend.
Complex Logic: Some Script logic doesn't map 1:1. Solution: Combine multiple Functions or use Payment/Delivery customizations.

Timeline Recommendation

March 2026: Inventory all Scripts, prioritize critical ones
April 2026: Migrate high-priority Scripts to Functions
May 2026: Migrate remaining Scripts, full testing
June 2026: Scripts deprecated — must be on Functions

Bottom Line

Migration is mandatory, not optional. The good news: Functions are more powerful, faster, and future-proof. The bad news: you have 3 months left. Start with your most critical discount Script. Get one migration under your belt before tackling the rest.

Frequently Asked Questions

What happens if I do not migrate Shopify Scripts by June 2026?

Script-based checkout customizations can stop applying correctly after the deadline. Discounts, shipping logic, and payment rules should be rebuilt as Shopify Functions before the cutoff.

Can Shopify Scripts be automatically converted to Functions?

No. The business logic has to be reviewed and rewritten in the relevant Shopify Functions API. Simple scripts may map cleanly, but complex scripts need testing and edge-case handling.

Which Functions should I use first?

Start with the Function type that matches your current Script: discount, delivery customization, payment customization, cart transform, or checkout validation.

How should I test the migration?

Use development stores, Shopify CLI, test carts, and real edge cases from previous orders. Do not deploy a Function until you have compared outputs against the old Script behavior.