Anthropic Hard-Cuts Claude Sonnet 4 and Opus 4 API Models on June 15

Anthropic’s official model deprecation schedule confirms a hard retirement for claude-sonnet-4-20250514 and claude-opus-4-20250514 on June 15, 2026. Unlike some cloud providers that offer extended grace periods, Anthropic’s documentation states requests to retired models will fail immediately — “the switch flips.”

Replacement Mapping

• Sonnet 4 (20250514 snapshot) → claude-sonnet-4-6
• Opus 4 (20250514 snapshot) → claude-opus-4-8

Impact on Agent Builders

Developers building agents with the Claude Agent SDK, LangChain, or custom API wrappers must update model strings before the deadline. Third-party routing layers (like model gateways) caching old IDs will propagate failures across downstream services.

API Parameter Changes

For Opus 4.7+ models including 4.8, sampling parameters (temperature, top_p, top_k) are deprecated and return 400 errors when non-default. This affects code that sets explicit temperature for reproducibility.

Timeline

• June 15, 2026: Sonnet 4 and Opus 4 (20250514) retired
• August 5, 2026: Opus 4.1 retired
• June 30, 2026: Claude Mythos Preview retired (migrate to claude-mythos-5)

Anthropic provides at least 60 days notice for publicly released model retirements.