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Claude Code Deprecates Fast Mode for Opus 4.8, With Removal Set for November 30

Claude CodeView original changelog

Claude Code 2.1.316 deprecates fast mode for Opus 4.8 as of October 30, 2026, and removes it on November 30, 2026. After removal, fast mode requests on Opus 4.8 return an error instead of falling back to standard Opus 4.8. Anthropic points users to Opus 5.5 to keep the speedup.

Key Takeaways

  • Fast mode for Opus 4.8 is deprecated as of October 30, 2026, and Claude Code 2.1.316 carries the notice.
  • Removal is scheduled for November 30, 2026, giving users about a month to change course.
  • After removal, fast mode requests on Opus 4.8 return an error rather than running at standard speed.
  • Anthropic states there is no fallback to standard Opus 4.8, so pinned configurations will fail instead of slowing down.
  • The recommended path is to migrate to Opus 5.5 to keep the speedup, though the release notes give no pricing terms for it.
  • Unattended runs, CI jobs and shared team settings are the most likely places for the change to cause surprise failures.

What changed

Claude Code 2.1.316 deprecates fast mode for Opus 4.8. The deprecation took effect on October 30, 2026, and the feature is scheduled for removal on November 30, 2026. Users who rely on fast mode with Opus 4.8 have one month to move.

What happens after removal

The release notes spell out an important detail about the failure mode. After November 30, a fast mode request on Opus 4.8 returns an error. It does not quietly fall back to standard Opus 4.8. Anyone with a script, alias, settings file or team convention that pins fast mode to Opus 4.8 should expect those requests to fail rather than run more slowly.

This differs from what many users may assume. A silent fallback would only cost speed. An error can break an automated run, a scheduled task or a CI job that was written when fast mode on Opus 4.8 was available.

How to keep the speedup

Anthropic's guidance in the release notes is to migrate to Opus 5.5 to keep the speedup. The notes do not list pricing or other terms for fast mode on Opus 5.5, so users should check their plan and usage settings before switching a shared workflow.

Who should act

Three groups are most exposed. Individual developers who toggled fast mode on while using Opus 4.8 and never revisited it. Teams that set Opus 4.8 as a pinned model alongside fast mode in shared configuration. And anyone running unattended sessions, where an error is more disruptive than a slow response. The practical step is to search configuration and scripts for Opus 4.8 fast mode usage now, and change the model before November 30.