# Anthropic: Major incident: Elevated errors for Claude Sonnet 5

**Summary:** Claude Sonnet 5 requests experienced elevated errors across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork, with major impact. The incident started at 2026-09-03 12:37 UTC and was resolved at 2026-09-03 12:56 UTC; the reported duration was 18 min. Anthropic implemented a fix and monitored results before resolution. _(machine-written, sol)_
- Kind: Major incident · Label: outage (model (Jev))
- Changed: 2026-09-03 12:37 UTC · Detected: 2026-10-17 18:21 UTC
- [Source: https://stspg.io/jt14jk41pjsf](https://stspg.io/jt14jk41pjsf)
- [Company: Anthropic](https://rewindex.com/company/anthropic.md)
- Versions: before (none: first archived) → after incident\_version:1/288w7p4hk1l1@bc48070a278f
- Change 1 of 1 for this incident

## What changed

**1. Added: Title**

```diff
+ Elevated errors for Claude Sonnet 5
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ resolved
```

**4. Added: Start time**

```diff
+ 2026-09-03 12:37 UTC
```

**5. Added: Resolved time**

```diff
+ 2026-09-03 12:56 UTC
```

**6. Added: Affected components**

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

**7. Added: Update** (investigating) · 2026-09-03 12:37 UTC

```diff
+ We are investigating elevated errors on requests to Claude Sonnet 5. We will provide an update as soon as possible.
```

**8. Added: Update** (monitoring) · 2026-09-03 12:47 UTC

```diff
+ A fix has been implemented and we are monitoring the results.
```

**9. Added: Update** (resolved) · 2026-09-03 12:56 UTC

```diff
+ This incident has been resolved.
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2026-09-03 12:37 UTC | Major incident: Elevated errors for Claude Sonnet 5 (this change) | outage |

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._


---
Canonical: https://rewindex.com/change/i0a4234a6cc1bd9 · Markdown: https://rewindex.com/change/i0a4234a6cc1bd9.md · JSON: https://rewindex.com/api/v1/changes/i0a4234a6cc1bd9 · Generated 2026-10-18T00:39:22.961Z