Observed 2 October 2026

Anthropic changed Claude Sonnet 4.5's status from active to deprecated, announcing on September 30, 2026 that it will be retired on November 30, 2026, with Claude Sonnet 5.5 as the recommended replacement.

what changed matterssummary written by a model — check it against the diff below

3 lines of binding language were added — this changes what someone is permitted or required to do.

+5 −1 · 031c64f → a390f82 · a390f82f2578 · live page

anthropic/model-deprecations.txt2 Oct 2026

53 unchanged lines
claude-sonnet-5-5 Active N/A Not sooner than September 28, 2027
claude-sonnet-5 Active N/A Not sooner than June 30, 2027
claude-sonnet-4-6 Active N/A Not sooner than February 17, 2027
claude-sonnet-4-5-20250929 Active N/A Not sooner than September 29, 2026
claude-sonnet-4-5-20250929 Deprecated September 30, 2026 November 30, 2026
claude-sonnet-4-20250514 Retired April 14, 2026 June 15, 2026
claude-3-7-sonnet-20250219 Retired October 28, 2025 February 19, 2026
claude-haiku-4-5-20251001 Active N/A Not sooner than October 15, 2026
1 unchanged line
claude-3-haiku-20240307 Retired February 19, 2026 April 20, 2026
Deprecation history
All deprecations are listed in the following sections, with the most recent announcements first.
2026-09-30: Claude Sonnet 4.5 model
On September 30, 2026, Anthropic notified developers using Claude Sonnet 4.5 of its upcoming retirement on the Claude API.
Retirement date Deprecated model Recommended replacement
November 30, 2026 claude-sonnet-4-5-20250929 claude-sonnet-5-5
2026-06-05: Claude Opus 4.1 model
This model was retired August 5, 2026.
On June 5, 2026, Anthropic notified developers using Claude Opus 4.1 of its upcoming retirement on the Claude API.
58 unchanged lines

Underlined words mark what moved within a rewritten line. Nothing here is interpreted — this is the difference between two captures, and the conclusion is yours.