If you are asking about a problem you are experiencing, please use the following template, as it will help us help you. If you have a different problem, please delete all of this text 
TIP 1: select at least one tag that further categorizes your topic. For example server for APM Server related questions, java for questions regarding the Elastic APM Java agent, or ui for questions about the APM App within Kibana.
TIP 2: Check out the troubleshooting guide first. Not only will it help you to resolve common problems faster but it also explains in more detail which information we need before we can properly help you.
Kibana version: 8.7.1
Elasticsearch version: 8.7.1
APM Server version: 8.7.1
APM Agent language and version: react.js / node.js
Browser version:
Original install method (e.g. download page, yum, deb, from source, etc.) and version:
Fresh install or upgraded from other version?
Is there anything special in your setup? For example, are you using the Logstash or Kafka outputs? Are you using a load balancer in front of the APM Servers? Have you changed index pattern, generated custom templates, changed agent configuration etc.
Description of the problem including expected versus actual behavior. Please include screenshots (if relevant):
I keep seeing the following error message in my ECK cluster:
[buyerportal-0 buyerportal] {"log.level":"error","@timestamp":"2023-05-19T06:46:40.752Z","log":{"logger":"elastic-apm-node"},"ecs":{"version":"1.6.0"},"message":"APM Server transport error (503): Unexpected APM Server response when polling config\nAgent configuration infrastructure is not ready. Please retry later."}
What's the root cause? How to resolve it?
Steps to reproduce:
1.
2.
3.
Errors in browser console (if relevant):
Provide logs and/or server output (if relevant):