PHP Warning: Undefined array key "host and "scheme" in canonical.php

Regrettably, a little while ago also PHP-FPM 8.1.17 Server has stopped as well.

Under the file

/etc/php/8.1/fpm/pool.d/www.conf

I may see:

pm = dynamic
pm.max_children = 5
pm.start_servers = 2
pm.min_spare_servers = 1
pm.max_spare_servers = 3
;pm.max_spawn_rate = 32
;pm.process_idle_timeout = 10s;
;pm.max_requests = 500

If I want to reduce child processes for PHP-FPM, how may I amend the above configuration?

Moreover, may you please confirm that I can manage the file

/etc/mysql/mariadb.conf.d/50-server-cnf

[server]
[mysqld]
pid-file                = /run/mysqld/mysqld.pid
basedir                 = /usr
bind-address            = 127.0.0.1
expire_logs_days        = 10
character-set-server  = utf8mb4
collation-server      = utf8mb4_general_ci
innodb_file_per_table = 1
max_allowed_packet = 64M
[embedded]
[mariadb]
[mariadb-10.6]

through Webmin → Servers → MariaDB Database Server → MariaDB Server Configuration

Thank you in advance.