#api-migration

OpenAI shuts down gpt-5, gpt-5-mini, gpt-5-nano, gpt-5-pro, o3 and o3-pro on December 11, 2026. The snapshots, the named replacements and what the switch costs.

OpenAI will remove GPT-4o, GPT-4o mini, GPT-4.1 and GPT-4.1 mini from its API on January 14, 2027. What breaks, what to switch to and what it costs.

Claude Sonnet 5.5 rejects thinking disabled, forced tool choice and three more settings. The exact errors and fixes, grouped by the model you run today.

OpenAI's DevDay is September 29 in San Francisco. What already shipped on the API, what retires on September 28, and the checklist to finish before the event.

Claude Fable 5.1 reasoning cannot be read by Opus 5 or Sonnet 5. Any router, retry or refusal fallback that moves a task down loses it silently. What to change.

Anthropic kept every per-token price and cut one line item 75%. Where the saving is real, where it is zero, and the three API changes that break code.

The v1.0 release swaps httpx for httpx2, sets a Python 3.10 floor, drops Text Completions, and makes AnthropicBedrock error when no region is set.

DeepSeek retires its deepseek-chat and deepseek-reasoner API aliases on July 24, 2026 at 15:59 UTC. The confirmed migration steps, plus the claims to watch.

OpenAI retires 13 model snapshots on July 23, 2026, including every pre-5.3 Codex variant. Replacements aren't 1:1, so pinned configs need testing first.

OpenAI launches GPT-5.2 and GPT-5.2-Codex optimized for agentic coding as GPT-4o retires February 13, 2026. Complete migration and implementation guide.