OpenAI shuts off o1, o3-mini, and other legacy models in the API today

#What happened

OpenAI is shutting down a batch of legacy model snapshots in its API today, October 23, 2026, per the notice posted on its official deprecations page on April 22, 2026. After today, API calls pinned to these snapshots stop working. Verified October 23, 2026.

Going offline today:

• o1 (o1-2024-12-17), substitute: gpt-5.6-sol
• o1-pro (o1-pro-2025-03-19), substitute: gpt-5.6-sol
• o3-mini (o3-mini-2025-01-31), substitute: gpt-5.6-sol
• o4-mini (o4-mini-2025-04-16), substitute: gpt-5.6-terra
• gpt-4-0613, substitute: gpt-5.6-sol
• gpt-4-turbo, substitute: gpt-5.6-sol
• gpt-4-1106-preview, substitute: gpt-5.6-sol
• gpt-4o-2024-05-13, substitute: gpt-5.6-sol
• gpt-3.5-turbo-0125, substitute: gpt-5.6-terra
• gpt-4.1-nano, substitute: gpt-5.6-luna
• gpt-image-1, substitute: gpt-image-2.5-sunburst or gpt-image-2.5-flare
• Fine-tuned removals: ft-gpt-3.5-turbo, ft-gpt-4, ft-gpt-4.1-nano-2025-04-14, ft-babbage-002, ft-davinci-002, each with a named GPT-5.6-family replacement

OpenAI says deprecated models get at least 6 months' notice for generally available models, and shutdown dates are exposed programmatically through the models list endpoint's shutdown_date field.

#Why it matters

Anything still pinned to these snapshots breaks today. The loud apps get fixed fast because someone notices; the real risk is the quiet automation: overnight scripts, agent steps, or pinned model calls nobody watches. Search your repos and environment variables for the retired model names, swap each for its named substitute, and run one real input through it, since newer models can answer in a different shape.

Sources: https://developers.openai.com/api/docs/deprecations and https://www.civic.com/bin/openai-old-models-off-today