# GitLab: Major incident: GitLab Duo Chat (classic) returning errors

**Summary:** _summary pending_
- Kind: Major incident · Label: major (vendor)
- Changed: 2025-09-04 23:33 UTC · Detected: 2026-10-18 05:08 UTC
- [Source: https://status.gitlab.com/pages/incident/5b36dc6502d06804c08349f7/68ba21d8d7b04805114d9eb0](https://status.gitlab.com/pages/incident/5b36dc6502d06804c08349f7/68ba21d8d7b04805114d9eb0)
- [Company: GitLab](https://rewindex.com/company/gitlab.md)
- Versions: before (none: first archived) → after incident\_version:188/68ba21d8d7b04805114d9eb0@3d795a475c8e
- Change 1 of 1 for this incident

Incident page (full timeline): [GitLab Duo Chat (classic) returning errors](https://rewindex.com/company/gitlab/incidents/68ba21d8d7b04805114d9eb0.md)
## What changed

**1. Added: Title**

```diff
+ GitLab Duo Chat (classic) returning errors
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ resolved
```

**4. Added: Start time**

```diff
+ 2025-09-04 23:33 UTC
```

**5. Added: Resolved time**

```diff
+ 2025-09-05 00:33 UTC
```

**6. Added: Affected components**

```diff
+ GitLab Duo
```

**7. Added: Update** (investigating) · 2025-09-04 23:33 UTC

```diff
+ Our team is currently investigating an issue with Duo Chat (classic). Users may experience A1004 errors. Duo Chat (Agentic) is working normally
```

**8. Added: Update** (investigating) · 2025-09-05 00:07 UTC

```diff
+ All messages to Duo Chat classic are currently receiving A1004 errors. Duo Chat (Agentic) is working normally. Our team is currently investigating. For more information, see https://gitlab.com/gitlab-com/gl-infra/production/-/issues/20483
```

**9. Added: Update** (resolved) · 2025-09-05 00:33 UTC

```diff
+ A recent change has been reverted and confirmed as the cause. Duo chat (Classic) is now working. For details, see https://gitlab.com/gitlab-com/gl-infra/production/-/issues/20483
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2025-09-04 23:33 UTC | Major incident: GitLab Duo Chat (classic) returning errors (this change) | major |

All GitLab changes: [timeline](https://rewindex.com/company/gitlab/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/i2468e462d22185 · Markdown: https://rewindex.com/change/i2468e462d22185.md · JSON: https://rewindex.com/api/v1/changes/i2468e462d22185 · Generated 2026-10-18T10:23:44.021Z