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

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

Major incidentcritical (vendor)Changed Detected status.claude.com (opens in new tab)
Summary

Summary pending. The diff below shows exactly what changed.

Incident page: the full timeline of updates

What changed

Struck in red is what Anthropic removed; blue is what they added. Muted text is unchanged context.

AddedTitle#1
Before: not present
After: Elevated errors for Claude Fable 5.1, Sonnet 5.5, and Haiku 5.5
AddedImpact#2
Before: not present
After: critical
AddedStatus#3
Before: not present
After: identified
AddedStart time#4
Before: not present
After: 2026-10-23 23:39 UTC
AddedAffected components#5
Before: not present
After: claude.ai, Claude API - api.anthropic.com, Claude Code, Claude Cowork
AddedUpdateinvestigating#6
Before: not present
After: We are investigating elevated errors on requests to Claude Fable 5.1. We will provide an update as soon as possible.
AddedUpdateidentified#7
Before: not present
After: 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.

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History of this incident

TodaySaturday, October 24Sat, Oct 24

2 incident changes

YesterdayFriday, October 23Fri, Oct 23

1 incident change

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