Migrate Claude Sonnet 4 and Opus 4 to v4.6 Before June Retirement
Anthropic · Sunset / Deprecation · · notable
Briefing for: Engineering
What happened
Anthropic has deprecated the Claude Sonnet 4 (claude-sonnet-4-20250514) and Claude Opus 4 (claude-opus-4-20250514) models. These legacy versions are scheduled for retirement on June 15, 2026, after which API calls to these identifiers will fail.
Why it matters
You have a two-month window to update your API integrations to the recommended 4.6 versions. This requires updating model identifiers and conducting regression testing to ensure that the newer model versions do not negatively impact existing prompt outputs or formatting.
What this enables
- If you use hardcoded model strings in your environment variables, schedule a task to swap them for the 4.6 series model identifiers.
- If you rely on specific JSON output schemas, run a validation suite against the 4.6 models to confirm parity before the June cutoff.
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