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

What to do

• Check whether your product depends on Elastic Cloud. Check your stack

  Paste a package.json, lockfile, Terraform or a list of domains at down.guide/stack to see every provider you depend on.

• Confirm your retries, queues and scheduled jobs caught up after the 7d 13h it lasted.

  Anything that failed between 2026-09-09 20:44 UTC and 2026-09-17 10:30 UTC may need a replay.

• Subscribe to Elastic Cloud's feed to hear about the next one first. RSS feed

  https://down.guide/feed?provider=elastic-cloud works in Slack (/feed subscribe), Discord feed bots and any RSS reader.

Updates from Elastic Cloud 4

1. identifiedSep 9, 2026, 8:44 PM UTC

   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.

   provider

2. identifiedSep 11, 2026, 2:25 PM UTC

   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

   provider

3. identifiedSep 11, 2026, 4:00 PM UTC

   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).

   provider

4. resolvedSep 17, 2026, 10:30 AM UTC

   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.

   provider

Corrections

None so far.

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