Claude API version 2026-10-21
Anthropic released Claude API version 2026-10-21 and new major SDK and ant CLI versions that send it by default, now licensed under Apache 2.0.
The client SDKs and the ant CLI now send API version 2026-10-21 by default. The versions are Python 2.0.0, TypeScript 1.0.0, C# 13.0.0, Go 2.0.0, Java 3.0.0, PHP 1.0.0, Ruby 2.0.0 and ant CLI 2.0.0. They also carry breaking changes that do not depend on the API version, and the license changes from MIT to Apache 2.0. The same day Anthropic added enforcement_status and enforcement_actions fields to user profiles, with a filter to list restricted or banned profiles.
- Date
- Wednesday 21 October 2026
- Lab
- Anthropic
- Kind
- infra
- Access
- closed API
The release notes list the changes only briefly. The migration guide was not read, so the specific API breaking changes are unconfirmed.
Sources
This record was checked against its sources on 21 October 2026. How we check