Creation cutoff
Twilio says new Functions Classic functions and assets cannot be created from 13 September 2026.
Buyer-intent answers
Twilio · Functions Classic · migration
Twilio Functions Classic Migration: Preserve Runtime and Webhook Parity in 2026
A Twilio-backed migration checklist for Functions Classic owners preparing for the September-to-October 2026 automatic move to the new Functions experience.
Primary query: Twilio Functions Classic migration September 13 October 26 2026 parity checklist · Updated 2026-09-07
Direct answer
What should a Twilio Functions Classic owner verify before and during the 2026 automatic migration?
Twilio says customers will no longer be able to create new Functions Classic functions and assets from 13 September 2026, and active Classic functions are scheduled for automatic migration between 14 September and 26 October 2026. Twilio plans to preserve URLs, function and asset names, environment variables and deployed code, but teams should still record a before-state and verify critical webhook, runtime, dependency and environment behaviour after migration so a preserved configuration is not mistaken for preserved application behaviour.
Practical sequence
What to do next
- 01
Inventory every active Functions Classic service, function URL, asset, environment variable, runtime dependency and upstream webhook that matters to production behaviour.
- 02
Capture a pre-migration acceptance set using synthetic requests and expected responses for the most important inbound and outbound flows.
- 03
Confirm that no new Classic-only build work is planned after 13 September 2026 and move future development to the supported Functions workflow.
- 04
After Twilio migrates an account, compare URLs, names, environment values, runtime/dependency behaviour and webhook responses against the pre-migration evidence.
- 05
Resolve differences before declaring the migration complete, then keep the test corpus so future runtime changes can be checked without relying on production incidents.
Decision facts
Migration window
Twilio plans to migrate active Classic functions between 14 September and 26 October 2026.
Planned preservation
Twilio says existing URLs, names, environment variables and deployed code will be migrated.
Boundaries
- — Twilio says no customer action is required for the automatic move, so this checklist is a parity and evidence control rather than a claim that every account needs engineering changes.
- — Do not place secrets or production environment-variable values into a public checklist; validate presence and behaviour inside your approved environment.
Free proof before paid workflow