The OpenAI Assistants API shuts down August 26, 2026
Every call to /v1/assistants, /v1/threads, and /v1/threads/runs stops working on August 26, 2026 — no degraded mode, no grace period. OpenAI will not auto-migrate Threads; the state migration is on you.
- Announced
- August 26, 2025
- Effective
- August 26, 2026
- Hard deadline
- August 26, 2026
All Assistants API endpoints return errors after August 26, 2026
OpenAI announced the deprecation on August 26, 2025 with a one-year runway. The official replacement is the Responses API plus the Conversations API, and OpenAI publishes a migration guide — but explicitly will not provide automated migration of existing Threads.
This is a developer-facing event: products built on the Assistants object model (assistants, threads, runs) must be rebuilt on the new primitives, and persisted conversation state must be carried over manually.
- Every integration calling the Assistants endpoints, at a hard date.
- Automatic thread persistence semantics — the new APIs model state differently.
- Internal assistants your team relies on, if whoever built them doesn't port them in time.
The vendor’s path: Migrate to the Responses API + Conversations API (OpenAI publishes a guide).
The exit lanes, mapped — including what doesn’t carry over.
Each lane below is covered by the Feature Parity Map: every workflow mapped to its replacement, a per-person playbook, adoption verified. Free during beta.
Teams using this forced rebuild as the moment to re-evaluate the whole stack — the end-user workflows map cleanly.
Not sure which way to go — or moving more than one tool? Run the free audit and see your whole stack’s overlap first.