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Elastic Cloud: Elastic Agent enrollment/check-in failures on 9.5.3 (and 9.4.6) with Fleet remote Elasticsearch output

Impact: majorStatus: resolvedStarted Resolved (8 d)4 updatesSource: stspg.io (opens in new tab)
Summary

A major incident caused Elastic Agents using Fleet's remote Elasticsearch output to crash-loop or fail enrollment/check-in after configuration updates on Fleet Server 9.5.3 and 9.4.6. It ran from 2026-09-09 20:44 UTC to 2026-09-17 10:30 UTC (7 days 13 h). Corrected releases 9.5.4 / 9.4.6 fixed the issue; all known affected deployments recovered.

Machine-written from the archived incident (Sol). Check the timeline before relying on it.

Timeline of updates

  1. identified

    We've identified a bug in Fleet Server 9.5.3 (also present in 9.4.6) that can cause Elastic Agents to crash-loop and go offline when Fleet pushes a configuration update, including enrollment, a policy change, or a routine revision bump. This only affects policies that use Fleet's remote Elasticsearch output feature. Recommendation: If you use Fleet's remote Elasticsearch output, do not upgrade to 9.5.3 or 9.4.6 until a fixed version is available. If you're already on an affected version and experiencing agent check-in failures, contact Support for remediation steps. A fix has been merged and will ship in the next 9.5.x and 9.4.x releases. Known Issue documentation: fleet-server#7791, elastic-agent#16542.

  2. identified

    We have patched Fleet Server versions 9.5.3 and 9.4.6 with corrected releases deployed as of September 10, 2026 at 21:20 UTC. - Upgrading to the current 9.4.6 or 9.5.3 releases will not be affected by this bug as the updated release contains the fix. - If you upgraded to 9.4.6 or 9.5.3 before 21:20 UTC on 10 September 2026, perform the following mitigation: 1. Force restart the Integration Server component of you affected deployment 2. Run cleanup procedures on affected Elastic Agents (see https://support.elastic.co/knowledge/bee1c75c) — required if agents failed to check in or remained offline after the Integration Server restart

  3. identified

    We have patched Fleet Server versions 9.5.3 and 9.4.6 with corrected releases deployed as of September 10, 2026 at 21:20 UTC. - Upgrading to the current 9.4.6 or 9.5.3 releases will not be affected by this bug as the updated release contains the fix. - If you upgraded to 9.4.6 or 9.5.3 before 21:20 UTC on 10 September 2026, perform the following mitigation: 1. Force restart the Integration Server component of you affected deployment 2. Run cleanup procedures on affected Elastic Agents (see https://support.elastic.co/knowledge/bee1c75c) — required if agents failed to check in or remained offline after the Integration Server restart IMPORTANT: The patched Fleet Server is not available outside Elastic Cloud Enterprise (ECE) Stack Packs and Elastic Cloud Hosted (ECH).

  4. resolved

    We have confirmed that Elastic Agents are no longer experiencing enrollment failures related to this issue. Corrected Fleet Server releases (9.5.4 / 9.4.6) have been available on Elastic Cloud Hosted and Elastic Cloud Enterprise stack packs since September 10, 2026, and all known affected deployments have confirmed recovery. If you upgraded to an affected release before that time and have not yet applied the mitigation, guidance is available here: https://support.elastic.co/knowledge/bee1c75c.

Rewindex changes for this incident

Impact, status and times are the vendor’s own, as last archived. View on stspg.io (opens in new tab). Elastic Cloud profile · Recent Elastic Cloud incidents · Markdown · JSON