Anthropic deprecates Claude Opus 4.1, API retirement set for August 5

Anthropic announced on June 5, 2026 that Claude Opus 4.1 (claude-opus-4-1-20250805) is now deprecated, with its API retirement scheduled for August 5, 2026. Developers using the model have 60 days to migrate to a supported replacement, with claude-opus-4-8 as the recommended target.

What's new

The deprecation is effective immediately — Claude Opus 4.1 remains accessible until August 5 but is no longer recommended for production use. After that date, all API calls to claude-opus-4-1-20250805 will fail.

Key dates:

• Deprecation date: June 5, 2026
• Retirement date: August 5, 2026
• Recommended replacement: claude-opus-4-8

The change applies across the Claude API, Claude Platform on AWS, and Microsoft Foundry. Anthropic provides at least 60 days notice before any publicly released model retires, giving teams the full window to evaluate replacements and update production code.

Developers can audit their exposure by exporting usage data from the Usage page in Claude Console and reviewing the CSV for any API key or project still calling the deprecated model ID.

Context

Claude Opus 4.1 was an intermediate model in the Claude 4 family, launched in August 2025. It has been superseded by the rapid cadence of the 4.x series.

Claude Opus 4.8, the designated replacement, launched May 28, 2026, bringing substantial upgrades: a 1M token context window enabled by default, 128k max output tokens, adaptive thinking that triggers extended reasoning only when a turn requires it, and support for computer use, the advisor tool, and task budgets. Claude Opus 4.8 also defaults to effort: high across all surfaces including Claude Code and the Messages API.

This deprecation is part of a broader lifecycle consolidation. Claude Sonnet 4 (claude-sonnet-4-20250514) and the original Claude Opus 4 (claude-opus-4-20250514) are both retiring June 15, 2026. Claude Haiku 3 was retired in April. Anthropic is retiring prior-generation models in step with each new generation launch.

Separately on June 7, Anthropic released Python SDK v0.107.1, a patch fixing an issue where the x-api-key header was not sent correctly for API-key authentication on Microsoft Foundry.

Why it matters

August 5 is the hard deadline requiring action. Two months is enough runway to benchmark and update model IDs in production, but teams with pipelines tuned to Opus 4.1's specific output characteristics should start testing Opus 4.8 now. Anthropic notes that deprecated models are "likely to be less reliable than active models" even before the cutoff.

One migration detail worth noting: on Claude Opus 4.8, setting temperature, top_p, or top_k to a non-default value returns a 400 error — the same behavior as Opus 4.7. Teams that previously set these parameters should remove them or review the migration guide before switching model IDs.