# Klaviyo: Major incident: Real-time segmentation delays

**Summary:** Klaviyo reported major real-time segmentation delays affecting a subset of customers, with segments up to 2.5 hours out of date. The incident started at 2026-03-27 04:46 UTC and lasted 29 min, resolving at 2026-03-27 05:15 UTC. Engineering identified a solution, and Klaviyo confirmed real-time processing was restored. _(machine-written, sol)_
- Kind: Major incident · Label: degradation (model (Jev))
- Changed: 2026-03-27 04:46 UTC · Detected: 2026-10-17 18:22 UTC
- [Source: https://stspg.io/0y8lyxjtwy4q](https://stspg.io/0y8lyxjtwy4q)
- [Company: Klaviyo](https://rewindex.com/company/klaviyo.md)
- Versions: before (none: first archived) → after incident\_version:249/k106gdf6wbw8@1c050a009a11
- Change 1 of 1 for this incident

## What changed

**1. Added: Title**

```diff
+ Real-time segmentation delays
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ resolved
```

**4. Added: Start time**

```diff
+ 2026-03-27 04:46 UTC
```

**5. Added: Resolved time**

```diff
+ 2026-03-27 05:15 UTC
```

**6. Added: Affected components**

```diff
+ Segmentation, Segments
```

**7. Added: Update** (monitoring) · 2026-03-27 04:46 UTC

```diff
+ Starting around 8:15 PM US Eastern 26th March, we began seeing delays in real-time segment processing for a subset of customers. Segments may be out of date by up to 2.5 hours. Engineering have identified a solution and are working to implement the fix shortly. We will continue to provide updates as real-time segmentation functionality is restored.
```

**8. Added: Update** (resolved) · 2026-03-27 05:15 UTC

```diff
+ Real-time segmentation is processing in real-time, and this incident has been resolved.
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2026-03-27 04:46 UTC | Major incident: Real-time segmentation delays (this change) | degradation |

All Klaviyo changes: [timeline](https://rewindex.com/company/klaviyo/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/idf3b30aad94ff6 · Markdown: https://rewindex.com/change/idf3b30aad94ff6.md · JSON: https://rewindex.com/api/v1/changes/idf3b30aad94ff6 · Generated 2026-10-18T00:57:31.243Z