OpenAI sets API kill dates for three GPT-5 models — migrate to GPT-6 Sol and Luna by April 2027

#What happened

OpenAI posted a deprecation notice dated October 1, 2026: three API models will be removed from the API on April 1, 2027, with six months' notice:

• gpt-5.1 → migrate to gpt-6-sol
• gpt-5.3-codex → migrate to gpt-6-sol
• gpt-5.4-nano → migrate to gpt-6-luna

#Why it matters

OpenAI's published policy promises at least 6 months of notice for generally available models, 3 months for specialized variants (its own example of a specialized variant is "Codex variants such as gpt-5.3-codex"), and about 2 weeks for preview models. The Codex model got the full six months — double what the policy requires. Contrast: OpenAI gave gpt-5.4-cyber only about 20 days (deprecated September 11, removed October 1), and Anthropic gave Claude Sonnet 4.5 only 61 days.

#Also deprecated October 1: text-to-speech models

The same day, OpenAI deprecated its legacy TTS models — tts-1, tts-1-hd, gpt-4o-mini-tts-2025-03-20, and gpt-4o-mini-tts-2025-12-15 — for removal on January 6, 2027, with migration to gpt-realtime-2.1-mini.

#What it means for you

These are API model IDs, not ChatGPT model-picker entries. If you only use ChatGPT, nothing in this notice changes what you see. If you call these models from your own code, service, or plugin, April 1, 2027 is the hard deadline. This follows the already-announced retirements: GPT-5.5 leaves ChatGPT/Codex on October 14, and custom GPTs retire December 11.

Verified October 4, 2026. Sources: https://platform.openai.com/docs/deprecations and https://mixed-news.com/en/openai-gpt-5-1-codex-nano-retired-april-2027-six-months-notice/