# Synthetic agents ICMP monitors are all of sudden failing

**URL:** https://discuss.elastic.co/t/synthetic-agents-icmp-monitors-are-all-of-sudden-failing/385541
**Category:** Synthetics
**Created:** [March 20, 2026, 7:17am UTC](https://discuss.elastic.co/t/synthetic-agents-icmp-monitors-are-all-of-sudden-failing/385541 "2026-03-20T07:17:27Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Whoami1980](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/whoami1980/32/147545_2.png) [@Whoami1980](https://discuss.elastic.co/u/Whoami1980)
#### Post date: [March 20, 2026, 7:17am UTC](https://discuss.elastic.co/t/synthetic-agents-icmp-monitors-are-all-of-sudden-failing/385541/1 "2026-03-20T07:17:27Z")

</div>

Our Synthetic agents ICMP monitors are all of sudden failing.

While looking through the agent logs. These are the message we see.

#message  
Possible transient error during checkin with fleet-server, retrying

#error.message  
status code: 400, fleet-server returned an error: BadRequest, message: Bad request: unable to decode checkin request: EOF

#message  
Creating new request to request URL [https://dhbhfbjksbjfbjfgbjfs.abcdefgh.com.xx:58200/api/fleet/agents/8d6eaae4-cbad-4395-a6ed-fd042f0afeb0/checkin](https://dhbhfbjksbjfbjfgbjfs.abcdefgh.com.xx:58200/api/fleet/agents/8d6eaae4-cbad-4395-a6ed-fd042f0afeb0/checkin)?

#message  
requester 0/2 to host [https://dhbhfbjksbjfbjfgbjfs.abcdefgh.com.xx:58200/](https://dhbhfbjksbjfbjfgbjfs.abcdefgh.com.xx:58200/) errored

#error.message  
Post "[https://dhbhfbjksbjfbjfgbjfs.abcdefgh.com.xx:58200/api/fleet/agents/8d6eaae4-cbad-4395-a6ed-fd042f0afeb0/checkin?](https://dhbhfbjksbjfbjfgbjfs.abcdefgh.com.xx:58200/api/fleet/agents/8d6eaae4-cbad-4395-a6ed-fd042f0afeb0/checkin?)": read tcp xx.xx.xx.xx:40938-\>xx.xxx.xx.xx:58200: read: connection timed out

Has anyone seen this before? Any guidance will be appreciated?