Sonnet 4 and Opus 4 models retired
Claude Sonnet 4 (claude-sonnet-4-20250514) and Claude Opus 4 (claude-opus-4-20250514) models retired. All requests return an error. Recommend upgrading to Claude Sonnet 4.6 and Claude Opus 4.8. Researchers can request ongoing access through the External Researcher Access Program.
Fetched July 13, 2026


