# Elastic Cloud: Replication bug causing slow recoveries

- Impact (vendor’s label): major
- Status: resolved
- Started: 2026-09-01 08:16 UTC · Resolved: 2026-09-30 20:44 UTC · Duration: 30 d
- Updates: 6 · Affected components: Elastic Cloud Hosted
- [Vendor status page: https://stspg.io/nx73hprsrgph](https://stspg.io/nx73hprsrgph)
- [Company: Elastic Cloud](https://rewindex.com/company/elastic-cloud.md)

## Summary

Elastic Cloud Hosted reported major degradation from 2026-09-01 08:16 UTC to 2026-09-30 20:44 UTC (29 days 12 h). In Elasticsearch 9.5.0, 9.5.1 and 9.5.2, bulk indexing could cause replica divergence, high disk usage and long-running recoveries. Elastic fixed the bug in 9.5.3 and advised affected customers to upgrade and follow workaround steps. _(machine-written, sol)_
## Timeline of updates

- **investigating** 2026-09-01 08:16 UTC: We are aware of a bug affecting customers on Elasticsearch versions 9.5.0, 9.5.1 and 9.5.2 where bulk index operations processed on the primary shard can result in divergence on the replicas resulting in high disk usage and long-running recoveries. The team is working on a fix. More information can be found on https://www.elastic.co/docs/release-notes/elasticsearch/known-issues\#elasticsearch-9.5.2-known-issues The next update will be in the next 2 hours or sooner if needed.
- **identified** 2026-09-01 11:07 UTC: We have identified the root cause and the team is working on a fix scheduled to be released in Elasticsearch version 9.5.3 What you can do: - If you have not yet upgraded to 9.5.\*, you are not affected as upgrades to 9.5 have been disabled until 9.5.3 is released - If you are already running 9.5 and experience the symptoms of this issue, please contact Elastic Support. More information can be found on https://www.elastic.co/docs/release-notes/elasticsearch/known-issues\#elasticsearch-9.5.2-known-issues
- **identified** 2026-09-01 15:46 UTC: The fix has been identified and backported to the Elasticsearch 9.5 patch branch. The teams are performing the needed validations before scheduling and rolling out the 9.5.3 release.
- **monitoring** 2026-09-03 12:13 UTC: Elasticsearch 9.5.3 has been released and all customers currently running 9.5.0, 9.5.1 or 9.5.2 are advised to update to this new version as soon as possible.
- **monitoring** 2026-09-03 15:47 UTC: Elasticsearch 9.5.3 has been released and all customers currently running 9.5.0, 9.5.1 or 9.5.2 are advised to update to this new version as soon as possible. Impacted customers are advised to follow the workaround steps from https://github.com/elastic/elasticsearch/issues/158212 after the upgrade.
- **resolved** 2026-09-30 20:44 UTC: This issue was resolved in the 9.5.3 release of Elasticsearch.  Customers running versions 9.5.0, 9.5.1, or 9.5.2 of Elasticsearch are advised to update to a newer version as soon as possible.

## Rewindex changes for this incident

- 2026-09-01 08:16 UTC: [Major incident: Replication bug causing slow recoveries](https://rewindex.com/change/iedeb5464aab1e4.md)


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Canonical: https://rewindex.com/company/elastic-cloud/incidents/l6zgdnvvg41j · Markdown: https://rewindex.com/company/elastic-cloud/incidents/l6zgdnvvg41j.md · JSON: https://rewindex.com/api/v1/companies/elastic-cloud/incidents/l6zgdnvvg41j · Generated 2026-10-18T11:47:31.358Z