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Claude platform release notes: fast mode deprecated on Opus 4.8

Author
Anthropic
Published
30 October 2026
Added
2 November 2026
Original
https://platform.claude.com/docs/en/release-notes/overview

Summary

On 2026-10-30 Anthropic deprecated fast mode for Claude Opus 4.8. It will be removed on 2026-11-30. After that date, requests to claude-opus-4-8 with speed: "fast" return an error. Anthropic points users to Opus 5.5, where fast mode is generally available.

Key points

  • Deprecated 2026-10-30; removal on 2026-11-30.
  • After removal, fast requests on Opus 4.8 fail; Claude Code's changelog (2.1.316) adds that they do not fall back to standard-speed Opus 4.8.
  • Replacement: Opus 5.5 fast mode (GA since 2026-10-15, $8 / $40 per 1M tokens), with a migration guide from Opus 4.8.
  • Only fast mode is deprecated. The Opus 4.8 model itself stays Active, with retirement "not sooner than May 28, 2027" on the deprecations page (checked 2026-11-02).

Why it matters

Any code or gateway config that sends speed: "fast" to Opus 4.8 has four weeks to move to Opus 5.5 or drop the flag, or it starts failing.