[Debian] ERROR: FPM initialization failed

Question

My VPS is running on Debian 10. I have installed PHP7.4 for my applications. When I try to restart PHP7.4 service (systemctl status php7.4-fpm.service), I get the following error. How can I fix this error?

Mar 27 02:22:21 xxx.xxx.xxxx systemd[1]: Starting The PHP 7.4 FastCGI Process Manager...

Mar 27 02:22:21 xxx.xxx.xxxx php-fpm7.4[12021]: [27-Mar-2022 02:22:21] WARNING: Nothing matches the include pattern '/etc/php/7.4/fpm/pool.d/*.conf' from /etc/php/7.4/fpm/php

Mar 27 02:22:21 xxx.xxx.xxxx php-fpm7.4[12021]: [27-Mar-2022 02:22:21] ERROR: No pool defined. at least one pool section must be specified in config file

Mar 27 02:22:21 xxx.xxx.xxxx php-fpm7.4[12021]: [27-Mar-2022 02:22:21] ERROR: failed to post process the configuration

Mar 27 02:22:21 xxx.xxx.xxxx php-fpm7.4[12021]: [27-Mar-2022 02:22:21] ERROR: FPM initialization failed

Mar 27 02:22:21 xxx.xxx.xxxx systemd[1]: php7.4-fpm.service: Main process exited, code=exited, status=78/CONFIG

Mar 27 02:22:21 xxx.xxx.xxxx systemd[1]: php7.4-fpm.service: Failed with result 'exit-code'.

Mar 27 02:22:21 xxx.xxx.xxxx systemd[1]: Failed to start The PHP 7.4 FastCGI Process Manage

Answer 1

From the error "No pool defined. at least one pool section must be specified in config file", it seems that there is no config file in folder /etc/php/7.4/fpm/pool.d/. You can create a file 'www.conf' with the following content in that folder. It will solve the problem.
 

[www]
listen = /run/php/php7.4-fpm.sock
user = www-data
group = www-data
listen.owner = www-data
listen.group = www-data
pm = ondemand
pm.max_children = 2
pm.process_idle_timeout = 10s
pm.max_requests = 100