We've released API version 2026-10-21. Migrating to API version 2026-10-21 shows how to upgrade. We've released new versions of the client SDKs and the ant CLI that send API version 2026-10-21 by default: Python SDK 2.0.0, TypeScript SDK 1.
Claude Platform breaking changes
The 3 releases whose own notes call out a breaking change, out of 81 the archive holds. Scattered one per release page, this is a run nobody can see; gathered, it is the shape of how often Claude Platform asks you to change your code.
- Tagged breaking
- 3 of 81 releases
- Roughly
- 1 in 27 releases held here
- Most recent
- 21 Oct 2026 today
- Across
- 6 months back to 16 Apr 2026
How this is decided
A release appears here because the word breaking is in the notes its publisher wrote, not because anyone here read the diff. That cuts both ways. A release that changed an API without using the word is missing from this page, and a release that used the word about something minor is on it. It is the publisher’s own signal, reported rather than judged, which is the same rule the security page follows.
Newest first
All Claude Platform releasesWe've launched Claude Opus 5 (claude-opus-5), a step-change improvement over Claude Opus 4.8. Claude Opus 5 supports a 1M token context window (both the default and the maximum), 128k max output tokens, and thinking on by default, at $5 / $
We've launched Claude Opus 4.7, our most capable model for complex reasoning and agentic coding, at the same $5 / $25 per MTok pricing as Opus 4.6. See What's new in Claude Opus 4.7 for capability improvements, new features, and the updated