ModelClock
Capability change
Capability change announced Apr 30, 2026
Anthropic documents a capability change: “We've retired the 1M token context window beta (context-1m-2025-08-07) for Claude Sonnet 4.5 and Claude Sonnet 4.”
- Hosting route
- First-party API
- Affected scope
- Not stated in the notice
- Announced
- Apr 30, 2026
- First seen by ModelClock
- Oct 5, 2026
What the provider published
platform.claude.com ↗
- We've retired the 1M token context window beta (
context-1m-2025-08-07) for Claude Sonnet 4.5 and Claude Sonnet 4. The beta header now has no effect on these models, and requests exceeding the standard 200k-token context window return an error. To use the 1M context window, migrate to Claude Sonnet 4.6 or Claude Opus 4.6 , where it's included at standard pricing with no beta header required.
Read from the provider's text; the quote is the provider's exact lines.