# Anthropic: Major incident: Elevated errors for Claude Sonnet 5.5

> 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 inve

Canonical: https://rewindex.com/change/i81083f272a2ce9
Last updated: 2026-10-27T09:24:02Z

**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, sol)_
- Kind: Major incident · Label: outage (model (Jev))
- Changed: 2026-10-27 09:14 UTC · Detected: 2026-10-27 09:24 UTC
- [Source: https://status.claude.com/incidents/0q89dylg9vjk](https://status.claude.com/incidents/0q89dylg9vjk)
- [Company: Anthropic](https://rewindex.com/company/anthropic.md)
- Versions: before (none: first archived) → after incident\_version:1/0q89dylg9vjk@9dcbd790d738
- Change 1 of 3 for this incident

Incident page (full timeline): [Elevated errors for Claude Sonnet 5.5](https://rewindex.com/company/anthropic/incidents/0q89dylg9vjk.md)
## What changed

**1. Added: Title**

```diff
+ Elevated errors for Claude Sonnet 5.5
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ investigating
```

**4. Added: Start time**

```diff
+ 2026-10-27 09:14 UTC
```

**5. Added: Affected components**

```diff
+ claude.ai, Claude API - api.anthropic.com, Claude Code, Claude Cowork
```

**6. Added: Update** (investigating) · 2026-10-27 09:14 UTC

```diff
+ We are investigating elevated errors on requests to Claude Sonnet 5.5. We will provide an update as soon as possible.
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2026-10-27 09:14 UTC | Major incident: Elevated errors for Claude Sonnet 5.5 (this change) | outage |
| 2026-10-27 09:43 UTC | [Incident updated: Elevated errors for Claude Sonnet 5.5](https://rewindex.com/change/r337646dd6dcdd1.md) | Normal progress |
| 2026-10-27 10:04 UTC | [Incident updated: Elevated errors for Claude Sonnet 5.5](https://rewindex.com/change/r9bd94423131637.md) | Normal progress |

Next: [change](https://rewindex.com/change/r337646dd6dcdd1.md) · All Anthropic changes: [timeline](https://rewindex.com/company/anthropic/changes.md)
_Diff excerpts are shown on normalized text: dates, counters and tokens appear as ‹date›, ‹count›, ‹tok›; noise-only edits are hidden. Rewindex shows the changed passages, not a copy of the page._

## 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).

- Canonical URL: https://rewindex.com/change/i81083f272a2ce9
- Citation: Anthropic, “Major incident: Elevated errors for Claude Sonnet 5.5” (2026-10-27 09:14 UTC). Archived by Rewindex: https://rewindex.com/change/i81083f272a2ce9 (CC BY 4.0).
- Markdown link: `[Anthropic: Major incident: Elevated errors for Claude Sonnet 5.5 (2026-10-27)](https://rewindex.com/change/i81083f272a2ce9)`


---
Canonical: https://rewindex.com/change/i81083f272a2ce9 · Markdown: https://rewindex.com/change/i81083f272a2ce9.md · JSON: https://rewindex.com/api/v1/changes/i81083f272a2ce9 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-11-04T13:38:54.829Z