Elasticsearch outage: Replication bug causing slow recoveries

Affected components

• Elastic Cloud Hosted

1. resolvedSep 30, 2026, 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.

2. monitoringSep 3, 2026, 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.

3. monitoringSep 3, 2026, 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.

4. identifiedSep 1, 2026, 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.

5. identifiedSep 1, 2026, 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

6. investigatingSep 1, 2026, 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.

What APIStatus.watch saw

• Sep 29, 2026, 14:31 UTCoperational → unknown
• Sep 29, 2026, 14:36 UTCunknown → operational

Other services with incidents at the same time

Overlapping incidents aren't necessarily related.

• Supabase: User unable to log in to Supabase DashboardCritical · Sep 1, 2026, 08:45 UTC
• Cursor: Investigating service degradationCritical · Sep 3, 2026, 13:41 UTC
• Intercom: Fin failures in Australia regionCritical · Sep 3, 2026, 14:29 UTC
• Supabase: Project Lifecycle Actions Showing increased error rates across all regionsCritical · Sep 4, 2026, 00:15 UTC
• Snowflake: INC20000199Critical · Sep 4, 2026, 07:34 UTC
• Mailgun: EU Messaging OutageCritical · Sep 4, 2026, 14:16 UTC
• dbt Cloud: dbt Platform not respondingCritical · Sep 4, 2026, 14:20 UTC
• GitBook: App and published docs unavailableCritical · Sep 5, 2026, 18:56 UTC
• Perplexity: Issue with usage based billingCritical · Sep 7, 2026, 22:52 UTC
• ReadMe: Admin interface outageCritical · Sep 8, 2026, 16:04 UTC

How often does Elasticsearch have incidents?

Elasticsearch reported 23 incidents in the last 90 days, 20 of them major or critical. A typical incident lasted 3h 35m. See Elasticsearch's uptime and incident history