We announced the deprecation of the Claude Sonnet 4.5 model (claude-sonnet-4-5-20250929)
By Steven Van ·
Retirement on the Claude API is set for November 30, 2026, and Anthropic recommends moving to Claude Sonnet 5.5.
Claude Sonnet 4.5 (claude-sonnet-4-5-20250929) is now deprecated on the Claude API, with retirement set for November 30, 2026. Anthropic announced the deprecation on September 30 and recommends migrating to Claude Sonnet 5.5 (claude-sonnet-5-5).
After the retirement date, requests to the model will fail. The dates apply to Anthropic-operated platforms: the Claude API, Claude Platform on AWS and Microsoft Foundry. Amazon Bedrock and Google Cloud set their own retirement schedules, so their dates can differ.
Anthropic says it gives at least 60 days' notice before retiring a publicly released model. To find where a deprecated model is still in use, open the Usage page in Claude Console, click Export, and review the CSV, which breaks usage down by API key and model.