Anthropic retired Claude Opus 4.1; requests to that model now return an error.

The operational issue is immediate: pinned traffic to Claude Opus 4.1 breaks instead of degrading.

The path is explicit: upgrade to Claude Opus 5 or request access through the External Researcher Access Program.

• Aug 11, 2026ChatGPT can now show restaurant reservation times from OpenTable, Resy, and Yelp.
• Aug 11, 2026Claude Opus 5 launched with 1M context, 128k max output, and thinking on by default.
• Aug 11, 2026Anthropic removed modelcard text covering Claude Fable 5 and Claude Mythos 5.

This is the world we build in. It moves this fast. We move with it.