# Claude: Major incident: Elevated errors for multiple models

**Summary:** Claude reported a major incident with elevated errors affecting multiple models across claude.ai, Claude API (api.anthropic.com), Claude Code and Claude Cowork. It started at 2026-09-03 13:26 UTC and was resolved at 2026-09-03 16:23 UTC, lasting 2 h 57 min. A fix was deployed; the vendor said customer impact ended at 16:16 UTC. _(machine-written, sol)_
- Kind: Major incident · Label: outage (model (Jev))
- Changed: 2026-09-03 13:26 UTC · Detected: 2026-10-17 18:22 UTC
- [Source: https://stspg.io/9xz4hhmd1jzn](https://stspg.io/9xz4hhmd1jzn)
- [Company: Claude](https://rewindex.com/company/claude.md)
- Versions: before (none: first archived) → after incident\_version:6/461yvfrzpwtt@238495420cba
- Change 1 of 1 for this incident

## What changed

**1. Added: Title**

```diff
+ Elevated errors for multiple models
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ resolved
```

**4. Added: Start time**

```diff
+ 2026-09-03 13:26 UTC
```

**5. Added: Resolved time**

```diff
+ 2026-09-03 16:23 UTC
```

**6. Added: Affected components**

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

**7. Added: Update** (investigating) · 2026-09-03 13:26 UTC

```diff
+ We are investigating elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5. We will provide an update as soon as possible.
```

**8. Added: Update** (identified) · 2026-09-03 13:41 UTC

```diff
+ We have identified the cause of elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and are working on a fix. We will provide an update as soon as possible.
```

**9. Added: Update** (identified) · 2026-09-03 13:50 UTC

```diff
+ An exhaustive list of affected models: Mythos/Fable 5.1, Mythos/Fable 5, Opus 5, Opus 4.8, Opus 4.6.
```

**10. Added: Update** (identified) · 2026-09-03 14:49 UTC

```diff
+ We are continuing to work on a fix for this issue.
```

**11. Added: Update** (identified) · 2026-09-03 15:25 UTC

```diff
+ The only affected models right now are Opus 4.8 and Opus 5. The rest of the models have recovered to baseline error rate.
```

**12. Added: Update** (monitoring) · 2026-09-03 16:06 UTC

```diff
+ A fix has been deployed for Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 and we are monitoring for recovery.
```

**13. Added: Update** (resolved) · 2026-09-03 16:23 UTC

```diff
+ The issue affecting Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5 has been resolved. Impact has ended as of 9:16 PT / 16:16 UTC.
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2026-09-03 13:26 UTC | Major incident: Elevated errors for multiple models (this change) | outage |

All Claude changes: [timeline](https://rewindex.com/company/claude/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._


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Canonical: https://rewindex.com/change/i6386734b3ed5c5 · Markdown: https://rewindex.com/change/i6386734b3ed5c5.md · JSON: https://rewindex.com/api/v1/changes/i6386734b3ed5c5 · Generated 2026-10-18T02:31:35.639Z