We have a problem with Wordpress sites and mod_lsapi. Occasionally 503 error is generated in Apache error_log
[Wed Mar 27 16:35:04.536230 2019] [lsapi:error] [pid 10459:tid 47611922413312] [client xxx.xxx.xxx.xxx:0] [host http://www.domain.com] Error on sending request(GET / HTTP/1.1); uri(/index.php) content-length(0): ReceiveAckHdr: nothing to read from backend (LVE ID XXX), check http://docs.cloudlinux.com/mod_lsapi_troubleshooting.html,, referer: https://www.domain.com
Strange things is that we cannot reproduce the error on 100%. No LVE limits were reached. Centos 7 with Cloudlinux, CageFS...
Maybe you can give us some clue where to search the problem?