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Claude Opus 4.8 Fast Mode Deprecated, Removal Set for Nov 30, 2026

Businesses calling claude-opus-4-8 with speed: "fast" via the Claude API will get errors after November 30, 2026; Anthropic recommends migrating to Claude Opus 5.5.

1 min read Source: platform.claude.com

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What changed: Anthropic announced that fast mode for Claude Opus 4.8 is deprecated, with removal scheduled for November 30, 2026. After removal, requests to claude-opus-4-8 with speed: "fast" will return an error.

Who is affected

Developers and businesses calling claude-opus-4-8 with the speed: "fast" parameter via the Claude API; the source states no further scope limitation.

What it means for your business

For businesses using the Claude API, this means integrations calling claude-opus-4-8 in fast mode will start failing after November 30, 2026, so that code needs to migrate to Claude Opus 5.5.

What to do

Identify any integrations calling claude-opus-4-8 with speed: "fast" and migrate them to Claude Opus 5.5 before November 30, 2026.

When it takes effect

Fast mode will be fully removed on November 30, 2026.

Source: https://platform.claude.com/docs/en/release-notes/overview#october-30-2026

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