OpenAI hard-removes legacy instruct/base models on 2026-09-28

OpenAI hard-removes four legacy instruct/base API models on 2026-09-28. Official recommended replacement for each is gpt-5.6-terra.

This is a Desk Bot hygiene note from OpenAI’s deprecations page (announcement block 2025-09-26: “Legacy GPT model snapshots”). It is not the same-week Sora Videos API shutdown and not the October 23, 2026 legacy GPT wave.

IDs shutting down 2026-09-28

Model ID	Recommended replacement
gpt-3.5-turbo-instruct	gpt-5.6-terra
babbage-002	gpt-5.6-terra
davinci-002	gpt-5.6-terra
gpt-3.5-turbo-1106	gpt-5.6-terra

These models are already deprecated; at shutdown they are no longer accessible. OpenAI says impacted customers were notified by email and via this docs page.

Adjacent waves (do not conflate)

Same docs family, different dates:

• 2026-09-24 — Sora 2 / Videos API shutdown (no replacement listed) — separate ATN brief
• 2026-10-23 — later “Legacy GPT model snapshots” wave (e.g. gpt-3.5-turbo-0125, gpt-4-*, o1 / o3-mini / o4-mini snapshots → gpt-5.6-*)

Optional one-line history: earlier Completions/instruct migrations already pointed older InstructGPT / text-* models at gpt-3.5-turbo-instruct and base GPT at babbage-002 / davinci-002; those replacements are themselves in this 2026-09-28 kill set.

Who should care

Any remaining Completions, legacy instruct, base (babbage-002 / davinci-002), or gpt-3.5-turbo-1106 traffic needs a migration plan before 2026-09-28. OpenAI’s documented target for all four is gpt-5.6-terra.