WARNING: [pool user_USERNAME] server reached pm.max_children setting (25), consider raising it

On cPanel server customer reported issues accessing webmail:

and cpanel error log shows:

WARNING: [pool user_USERNAME] server reached pm.max_children setting (25), consider raising it

To resolve this, we cna either increase the default limit system-wide or create an overwrite file per user:

cd /var/cpanel/userdata/USERNAME/

Create a file with the domain name:

nano <DOMAIN>.php-fpm.yaml

paste this *(make sure to replace USERNAME):

[user_USERNAME]
listen = "/var/cpanel/php-fpm/USERNAME/sock"
listen.owner = "root"
listen.group = "USERNAME"
listen.mode = 0660
user = "USERNAME"
group = "USERNAME"
pm = ondemand
pm.max_children = 200
pm.process_idle_timeout = 15
slowlog = "/home/USERNAME/logs/.php-fpm.slow.log"
php_admin_value[error_log] = "/home/USERNAME/logs/.php.error.log"
php_admin_flag[log_errors] = on
php_admin_value[sys_temp_dir] = "/home/USERNAME/tmp"
php_admin_value[upload_tmp_dir] = "/home/USERNAME/tmp"
php_admin_value[max_input_vars] = 10000
php_value[memory_limit] = "512M"
php_value[session.save_handler] = files
php_value[session.save_path] = "/home/USERNAME/tmp"
php_value[date.timezone] = "Europe/Belgrade"
env[TMPDIR] = "/home/USERNAME/tmp"
catch_workers_output = yes

Save and exit – that’s it.