OpenAI Assistants API was sunset on August 26, 2026
OpenAI says the Assistants API was officially sunset on August 26, 2026 and is no longer available. Remaining integrations must move to the Responses API; Conversations provide durable state where needed.
Required action
Migrate remaining integrations to Responses and Conversations using application-owned configuration and stored message history. Validate tools, state, safety, latency and cost. Avoid a new dependency on reusable prompt objects, whose separate shutdown date is November 30, 2026.
Scope and evidence limits
OpenAI API; no regional exception documented
The Assistants API is no longer available on the OpenAI API. Calls that still depend on Assistants, Threads, Runs or Run Steps require migration to supported Responses-era primitives.
not_tested
Official sources
- developers.openai.com · migration
- developers.openai.com · deprecations
- developers.openai.com · migrate-from-prompt-object
Affected components
Assistants API
Affected users
Developers running production assistants on the deprecated Assistants API.
Migration guidance
Move instructions, model settings and tool definitions into versioned application configuration. Use Responses and Conversations, rebuilding history from messages already stored by your application; retired Threads retrieval no longer works. Reusable prompt objects and v1/prompts are scheduled to shut down November 30, 2026, so do not adopt them as a new long-lived dependency.
Correction history
- 2026-08-27: Official post-sunset verification changed the record from an upcoming deadline to completed; OpenAI now says the Assistants API is no longer available.
- 2026-09-21: The migration advice omits two current official warnings: retired Threads history retrieval no longer works, and reusable prompt objects have their own retirement.