Anthropic deprecates fast mode for Claude Opus 4.8, pushing migration to Opus 5.5

2026-10-30

Anthropic's API changelog, updated October 30, 2026, 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; Anthropic directs affected users to migrate to Claude Opus 5.5 to continue using fast mode.

Significance 2: A routine API deprecation notice rather than a new capability or price change, but it touches the model behind two current verdicts and nudges usage toward the newer Opus 5.5.

technology financial Release

Sources

primary Claude Platform release notes retrieved 2026-10-31

Models

Claude Opus 4.8

Affected axes

Output speed

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