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App using Claude Sonnet 4.5? Anthropic retires it on November 30, 2026

Ship ItChecked against the official source

Source checked 27 Oct 2026 · Published 29 Oct 2026 · Last reviewed 29 Oct 2026 · By Ctrl+Z Therapy (how we test)

The short answer

Anthropic's model deprecations page says that on September 30, 2026, Anthropic notified developers using Claude Sonnet 4.5 of its upcoming retirement on the Claude API. The retirement date for claude-sonnet-4-5-20250929 is November 30, 2026, and the recommended replacement is claude-sonnet-5-5. Requests to models past the retirement date will fail.

What to do

  1. Search your app's code and settings for the model name claude-sonnet-4-5-20250929.
  2. Switch it to claude-sonnet-5-5, and test a real request before you ship.
  3. Ask your AI tool: "Find every Claude model name in this app's code and settings. If one is claude-sonnet-4-5-20250929, switch it to claude-sonnet-5-5 and test one request."

Good to know

  • The dates apply to Anthropic-operated platforms: the Claude API, Claude Platform on AWS, Claude Models on Google Cloud (Anthropic managed) and Microsoft Foundry. Amazon Bedrock and Claude Models on Google Cloud (Google managed) set their own retirement schedules.

Source

Checked on 27 Oct 2026. Prices, limits and settings change, so check the source before you rely on them.

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