I had the same issue recently but my solution was different. I’m running Icingaweb2 on top of an nginx webserver. The cause of the error was in my upstream-php configuration that required a change due to the debian-buster update I did beforehand:
upstream icingaweb2 {
#server unix:/var/run/php/php7.0-fpm.sock;
server unix:/var/run/php/php7.3-fpm.sock;
}
After a brief restart of my webserver the error was gone immediatley. Due to my php.ini configuration my situation was that a cli deployment via icingacli director config deploy was working fine, but icingaweb2-deployments failed. I guess I have to dive a little deeper into my php.ini file because php-cli’s configuration is more robust than php itself cause apparently cli took use of the right socket automatically.