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ChangesAnthropicElevated errors for Claude Sonnet 5.5

Anthropic: Major incident: Elevated errors for Claude Sonnet 5.5

Major incidentoutage (model (Jev), 99%)Changed Detected status.claude.com (opens in new tab)
Summary

Anthropic reported a major incident involving elevated errors on Claude Sonnet 5.5 requests across claude.ai, Claude API - api.anthropic.com, Claude Code, and Claude Cowork. It started at 2026-10-27 09:14 UTC and was still open when archived, with 0 min elapsed at the last update; Anthropic was investigating, with no cause or fix stated.

Machine-written from the diff below (Sol; type: incident outage). Check the diff before relying on it.

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 Sonnet 5.5
AddedImpact#2
Before: not present
After: major
AddedStatus#3
Before: not present
After: investigating
AddedStart time#4
Before: not present
After: 2026-10-27 09:14 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 Sonnet 5.5. We will provide an update as soon as possible.

First version of this incident archived by Rewindex. View the live incident (opens in new tab).

Archive proof

Rewindex commits each version of an incident it captures to a daily checkpoint, chains it to the day before, and has the checkpoint timestamped by FreeTSA and DigiCert. That proves this record existed by then and has not been changed since, by anyone, Rewindex included.

How the archive is checked, and what it cannot prove.

History of this incident

Tuesday, October 27

3 incident changes

Cite this

Major incident: Elevated errors for Claude Sonnet 5.5 on Anthropic’s status page, changed 2026-10-27 09:14 UTC (change 1 of 3).

Title
Major incident: Elevated errors for Claude Sonnet 5.5
Vendor
Anthropic
Date
URL
https://rewindex.com/change/i81083f272a2ce9

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