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Sweep 25 Sep 2026 · 19:33Z Build v2.1.283 504 read Stable v2.1.274 Latest v2.1.283 Next v2.1.283 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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whats-new-opus-5-5 changedmodels/opus-5-5/whats-new-opus-5-5

Nearest release: v2.1.283, published 3 hours after this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

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8888 
8989## Refusals and fallback
9090 
91Claude Opus 5.5 ships with safety classifiers, and everything in [Refusals and fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback) applies. A declined request returns HTTP 200 with `stop_reason: "refusal"` and a [`stop_details`](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#refusal-response) object naming the policy area, so handle refusals and configure fallback: retry on another model with [server-side fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback) (`fallbacks: "default"`, in beta, retries on the model Anthropic recommends for that category), the [SDK middleware](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#client-side-fallback), or your own retry.
91Claude Opus 5.5 ships with safety classifiers, and everything in [Refusals and fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback) applies. A declined request returns HTTP 200 with `stop_reason: "refusal"` and a [`stop_details`](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#refusal-response) object naming the policy area, so handle refusals and configure fallback: retry on another model with [server-side fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback) (`fallbacks: "default"`, in beta, retries on the model Anthropic recommends for that category), the [SDK middleware](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#client-side-fallback), or your own retry. Whether a refusal that arrives before any output is billed depends on its refusal category, and it counts against your rate limits either way; see [How refusals are billed](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#how-refusals-are-billed).
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9393## Pricing
9494 
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