Corrected: Anthropic deprecates Claude Sonnet 4.5 on the API, with retirement on November 30

ClaudeRetirementAnnounced

Correction: Corrected 22 Oct 2026: added the platforms Anthropic names. The date applies to the Claude API, Claude Platform on AWS and Microsoft Foundry; Amazon Bedrock and Google Cloud set their own dates. An earlier version said the source didn't specify them.

Anthropic announced the deprecation of Claude Sonnet 4.5 (claude-sonnet-4-5-20250929).

It will be retired on the Claude API on November 30, 2026.
Anthropic recommends migrating to Claude Sonnet 5.5 (claude-sonnet-5-5).
Anthropic's deprecations page says it notified developers using Sonnet 4.5 on September 30.

Who can use it: Developers calling claude-sonnet-4-5-20250929 on the Claude API. Applies to the Claude API, Claude Platform on AWS and Microsoft Foundry. Amazon Bedrock and Google Cloud set their own dates.
When: 2026-11-30 · date only
Announced September 30, 2026. Retirement is scheduled for November 30, 2026, a calendar date rather than an exact time.

Claude Platform release notes · Claude API model deprecations Announced 2026-09-30 · date only

Read the official announcement for access details. Availability can depend on your plan, region or workplace settings.