Anthropic releases the first new Claude API version in three years, 2026-10-21: the temperature, top_p and top_k parameters are removed
Prepared by Sintelligent with the help of SI. Published in SI: . Updated: .
Claude developers will have to update their code: there are no longer settings for response randomness, and the old API version still works for now.
Anthropic introduced API version 2026-10-21, the first since 2023-06-01. According to the migration guide, a request that sends temperature, top_p or top_k now returns a 400 error even if the value equals the default; without them, sampling uses the defaults, including a temperature of 1.0, just like 2023-06-01 requests that omit them. Models that already accepted only the default values behave as before. New major SDK versions that use it by default were released with it: Python 2.0.0, TypeScript 1.0.0, Go 2.0.0, Java 3.0.0, C# 13.0.0 and the ant command-line tool 2.0.0. The SDKs and the tool now send the API key in an Authorization: Bearer header instead of X-Api-Key, so proxies or gateways that read the old header need fixing; the new SDK versions are licensed under Apache 2.0 instead of MIT. According to Habr, a 400 error is now also returned for documents in assistant messages and for non-empty citations in text blocks of user messages. Older SDK versions keep sending 2023-06-01.
Sources 2