Claude Opus 4.1

Model at Anthropic

82nd of 418 on Arena text

Claude Opus 4.1 does not have a researched profile yet. Everything here comes from its recorded changes and public listings, each linked to its source.

The basics

As of Nov 1

Status: Retired Aug 5, 2026

Updates

Aug 5

Retired

Claude Opus 4.1 retired

Requests to claude-opus-4-1-20250805 on the Claude API now return an error. It remains on Bedrock and Google Cloud.

Action needed:: Switch to Claude Opus 5 or newer.

Jun 5

Retiring

Claude Opus 4.1 deprecated

Anthropic announced that claude-opus-4-1-20250805 would retire on the Claude API on August 5, 2026.

Action needed:: Migrate to Claude Opus 4.8 or newer.

Sep 17

Quality report · Confirmed by the lab

Anthropic confirms three infrastructure bugs degraded Claude responses in August and September 2025

Anthropic published a postmortem saying three separate infrastructure bugs, the first introduced on August 5, intermittently degraded Claude's response quality until early September. A load balancing change on August 29 increased affected traffic. The Hacker News thread drew 381 points and 116 comments.

Full changelog, by month