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minorArchivedAnthropicv5.1, 5.5

Anthropic: Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5

  1. Investigating(done)
  2. Trending(skipped)
  3. Workaround available(skipped)
  4. Resolved(done)
  5. Archived

Executive summary

Elevated error rates have been observed for requests to Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5. The issue is being addressed by the team.

No verified workaround yet

This incident was resolved upstream without a reported workaround.

Official fix
Technical root cause

The cause of elevated errors on requests to Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5 has been identified as a configuration issue in fast mode requests to Opus 5.5.

Evidence

1 report · 1 StatusShow
  1. [1]
    Status First report
    Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5(opens official status page in a new tab)

    Investigating: We are investigating elevated errors on requests to Claude Fable 5.1. We will provide an update as soon as possible. Identified: We have identified the cause of elevated errors on requests to Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5, as well as fast mode requests to Opus 5.5 and are working on a fix. We will provide an update as soon as possible. Monitoring: We are seeing success rates return to normal for all affected models, and are continuing to monitor to ensure no…

    by anthropic status

Timeline

  1. First report on status page

    Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5

    Source
  2. Official statement

    Investigating: We are investigating elevated errors on requests to Claude Fable 5.1.

    Source
  3. Status changed

    Status changed: new → resolved (official status page reports resolution).

  4. Status changed

    Status changed: resolved → archived (resolved more than 14 days ago).