# Claude Code 2.1.316: fast mode on Opus 4.8 is deprecated, with removal on 30 November 2026 Canonical: https://clawdocx.com/blog/claude-code-2-1-316-fast-mode-deprecation Author: Mira Castellan Published: 2026-10-31 Updated: 2026-10-31 > Claude Code 2.1.316 deprecates fast mode on Claude Opus 4.8 and sets removal for 30 November 2026, after which those requests return an error. Fast mode on Claude Opus 4.8 is going away on 30 November 2026, and when it does those requests will return an error rather than fall back to standard speed. If you run Claude Code with `/fast` on Opus 4.8, move to Opus 5.5 before that date. Anthropic's stated migration path is Opus 5.5, where fast mode is generally available rather than a research preview. The notice arrived in the Claude Code changelog entry for 2.1.316, dated 31 October 2026, and Anthropic's API documentation carries the same date independently. ## What exactly did Anthropic deprecate? The changelog entry is one sentence and worth reading closely, because it rules out the behaviour most people would assume: > Deprecated fast mode for Opus 4.8 as of October 30, 2026; it will be removed on November 30, 2026. After removal, fast mode requests on Opus 4.8 return an error and do not fall back to standard Opus 4.8. Migrate to Opus 5.5 to keep the speedup The deprecation is scoped to one model. Fast mode itself is not being retired, and the `/fast` toggle is unchanged. What ends is the combination of fast mode and Opus 4.8. Anthropic's API documentation states the same thing for direct API users, in a warning on its fast mode page: fast mode on Claude Opus 4.8 "is deprecated and will be removed on November 30, 2026", after which "requests to `claude-opus-4-8` with `speed: "fast"` will return an error." ## Why does the no-fallback detail matter? Because it changes a cost question into an availability question. A deprecation that quietly dropped you to standard speed would cost you latency and nothing else. This one fails the request instead. That makes it something to fix before the date rather than after. Anything running unattended on Opus 4.8 with fast mode on, a scheduled job or a CI step, will start erroring on 30 November rather than slowing down. There is no behaviour to degrade gracefully into. ## What does fast mode cost on each model? Anthropic's API pricing table gives the fast mode rates, and the Claude Code page repeats them. Note that Opus 5.5, the migration target, is the cheaper of the two tiers. | Model | Fast mode input (per MTok) | Fast mode output (per MTok) | Fast mode status | |---|---|---|---| | Claude Opus 5.5 | $8 | $40 | Available | | Claude Opus 5 | $10 | $50 | Research preview | | Claude Opus 4.8 | $10 | $50 | Deprecated, removal 30 November 2026 | Moving from Opus 4.8 to Opus 5.5 therefore lowers the fast mode rate as well as keeping the speedup. Anthropic describes fast mode as up to 2.5x faster at a higher cost per token, priced as a multiplier on standard rates across the full context window. For how fast mode interacts with the rest of Claude Code billing, see our [Claude Code pricing breakdown](/blog/claude-code-pricing). ## Why does the Claude Code fast mode page still say Opus 4.8 is available? This is the part to be careful about, because the page a reader would most likely check is the one that has not caught up. When we fetched `https://code.claude.com/docs/en/fast-mode` on 31 October 2026, its opening note still read that "fast mode for Claude Opus 5 and Claude Opus 4.8 is in research preview", its pricing table still listed Opus 4.8 at $10 and $50 as a current option, and it carried no deprecation notice for Opus 4.8 anywhere. The only fast mode deprecation that page documents is the earlier one for Opus 4.7. Two of the three vendor pages agree on the removal, so this is a stale reference page rather than a genuine disagreement about what is happening. The changelog and the API documentation are the ones to follow. We checked the Claude Code fast mode page in full for deprecation wording and found none; that is a statement about that page on that date, not about every page Anthropic publishes. ## Has Anthropic done this before? Yes, and the shape is the same, which is the best guide to how firm the date is. The Claude Code fast mode page records that fast mode for Opus 4.7 "was deprecated on June 25, 2026, and removed on July 24, 2026", roughly a one-month gap between notice and removal. The Opus 4.8 window is 30 October to 30 November, the same interval. One difference is worth noting: fast mode on Opus 4.8 is a research preview feature, and the Claude Code page's own research preview section says availability and pricing for it are subject to change. A removal on a month's notice is consistent with that status. ## What else landed in 2.1.314 and 2.1.316? Two changes in the same two releases are worth a look while you are upgrading. Version 2.1.314, dated 30 October 2026, added `permissions.blockWritesOutsideWorkingDirectories`, which makes the Write, Edit and NotebookEdit tools refuse paths outside the working directories in every permission mode. That is the write-side counterpart to the existing read-side setting, and it applies regardless of permission mode, which is what makes it useful as a guardrail rather than a prompt. Version 2.1.316 also changed server-managed settings for Team and Enterprise logins: settings fetched from Anthropic's API now apply without an approval prompt, and a stored copy that does not verify is refused. Administrators should know that a policy change now reaches developers without anyone clicking through a prompt. For the previous round of managed-settings and MCP changes in this release series, see our write-up of [the 2.1.305 MCP allowlist change](/blog/claude-code-2-1-305-mcp-allowlist-change). ## What should you do before 30 November? 1. Check whether you are on Opus 4.8 at all. Run `claude --version` and `/model`. Opus 5.5 has been the fast mode default since v2.1.280, so if you have not pinned a model you are probably already clear. 2. If you have pinned Opus 4.8 and use `/fast`, switch to Opus 5.5 with `/model`. 3. Check unattended callers separately. A scheduled task, CI step or SDK caller that pins `claude-opus-4-8` with `speed: "fast"` will error after the date, and it will not report a latency problem first. 4. If you are on the API, Anthropic links a dedicated migration guide for moving from Opus 4.8 to Opus 5.5 from the warning on its fast mode page. Fast mode is not available on Amazon Bedrock, Google Cloud's Agent Platform, Microsoft Foundry or Claude Platform on AWS, so this deprecation does not reach those deployments. More background on the platform is on our [Claude Code hub](/ai-agents/claude-code). ## Frequently asked questions **When does fast mode stop working on Claude Opus 4.8?** On 30 November 2026. The Claude Code changelog entry for 2.1.316, dated 31 October 2026, says fast mode for Opus 4.8 was deprecated as of 30 October 2026 and will be removed on 30 November 2026. Anthropic's API documentation carries the same removal date. **What happens if I keep fast mode on Opus 4.8 after the removal date?** The request returns an error. The changelog is explicit that requests do not fall back to standard Opus 4.8, so a session that relies on the fallback will fail rather than quietly run slower. On the API side the same applies to requests to claude-opus-4-8 with speed set to fast. **What should I switch to?** Anthropic's stated migration path is Claude Opus 5.5, which is where fast mode is generally available rather than in research preview. Opus 5.5 has been the fast mode default in Claude Code since v2.1.280, so many users are already on it and are unaffected. **Does this remove fast mode from Claude Code altogether?** No. Only fast mode on Opus 4.8 is being removed. Fast mode remains available on Opus 5.5, and the Claude Code documentation also lists Opus 5 as a research preview. The /fast toggle itself is unchanged. **Why does the Claude Code fast mode page still list Opus 4.8 as available?** That page had not been updated when we checked it on 31 October 2026. It still presents fast mode on Opus 5 and Opus 4.8 as a research preview and carries no deprecation notice, while the changelog and the API documentation both record the removal date. Treat the changelog and the API page as current here. ## Sources - [Claude Code changelog](https://code.claude.com/docs/en/changelog) - [Claude Code docs: fast mode](https://code.claude.com/docs/en/fast-mode) - [Claude API docs: fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode)