WordPress site health check: utf8mb4 requires a newer client library

Issue

• After installing MariaDB 10.6 WordPress site health check reports that

  utf8mb4 requires a newer client library

Environment

• CloudLinux OS
• MariaDB 10.6
• Alt-PHP used on the website

Solution

1. Switch from CloudLinux mysqli PHP module to the PHP native nd_mysqli module

2. Edit the /etc/my.cnf and add the following:

   [client]
   default-character-set=utf8mb4
   
   [mysql]
   default-character-set=utf8mb4
   
   [mysqld]
   character-set-server=utf8mb4
   character_set_client=utf8mb4
   collation-server=utf8mb4_general_ci

3. Restart MariaDB server

   # service mysqld restart

Cause

• Client library version fetched from MariaDB driver does not meet the minimal version number hardcoded in wp-admin/includes/class-wp-site-health.php code
• Starting from MariaDB 10.6 the utf8 character set (and related collations) is now by default alias for utf8mb3
• MariaDB 10.6 support is yet to be implemented

Useful links

Changes and Improvements in MariaDB 10.6 - MariaDB Knowledge Base