# Census: Major incident: Sync might be failing with mismatch errors

**Summary:** Census reported a major Sync Engine incident where some syncs failed with mismatch errors, starting 2025-04-04 22:40 UTC and resolved 2025-04-05 16:23 UTC (17 h 42 min). Census attributed failures to a performance issue, said errors could appear after the problem was resolved, and advised customers to rerun affected syncs. _(machine-written, sol)_
- Kind: Major incident · Label: outage (model (Jev))
- Changed: 2025-04-04 22:40 UTC · Detected: 2026-10-17 18:22 UTC
- [Source: https://stspg.io/sj2xqkwhys9d](https://stspg.io/sj2xqkwhys9d)
- [Company: Census](https://rewindex.com/company/census.md)
- Versions: before (none: first archived) → after incident\_version:136/dc644lcgv75n@9049c4fb5f20
- Change 1 of 1 for this incident

## What changed

**1. Added: Title**

```diff
+ Sync might be failing with mismatch errors
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ resolved
```

**4. Added: Start time**

```diff
+ 2025-04-04 22:40 UTC
```

**5. Added: Resolved time**

```diff
+ 2025-04-05 16:23 UTC
```

**6. Added: Affected components**

```diff
+ Sync Engine
```

**7. Added: Update** (investigating) · 2025-04-04 22:40 UTC

```diff
+ We are currently investigating issue with some syncs failing with mismatch errors.
```

**8. Added: Update** (monitoring) · 2025-04-04 23:00 UTC

```diff
+ We experienced a performance issue from ~3:00-3:15pm Pacific that may have caused some syncs to fail with a message about "mismatch counts".  We believe we have resolved the problem, but syncs that encountered the issue may not report an error until sometime after the fact, so errors may continue to trickle in. If you encounter this error, please attempt to rerun your sync.  If a rerun does not succeed, please contact support.
```

**9. Added: Update** (monitoring) · 2025-04-05 01:18 UTC

```diff
+ This issue is resolved.
```

**10. Added: Update** (monitoring) · 2025-04-05 16:21 UTC

```diff
+ We are continuing to monitor for any further issues.
```

**11. Added: Update** (resolved) · 2025-04-05 16:23 UTC

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

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2025-04-04 22:40 UTC | Major incident: Sync might be failing with mismatch errors (this change) | outage |

All Census changes: [timeline](https://rewindex.com/company/census/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/i8a5838b9185edf · Markdown: https://rewindex.com/change/i8a5838b9185edf.md · JSON: https://rewindex.com/api/v1/changes/i8a5838b9185edf · Generated 2026-10-18T01:30:31.609Z