Error 503, ReceiveAckHdr: nothing to read from backend

Issue

Wordpress website is inaccessible giving 503 error.

There are following errors in logs:

[lsapi:error] Error on sending request(GET / HTTP/2.0); uri(/) content-length(0): ReceiveAckHdr: nothing to read from backend (LVE ID ****),

Environment

• LSAPI
• CloudLinux OS

Solution

One of the possible reasons on Wordpress could be the missing .htaccess file.

Add the .htaccess file to the ~/public_html/

Useful links

The mod_lsapi troubleshooter advanced 

Why Wordpress htaccess is important