Step 3: Replace default version of audit log file with MySQL version
Since you are using MySQL to host the Pentaho Repository, you need to replace the audit_sql.xml file with one that is configured for MySQL. If you are using MariaDB, use the same audit_sql.xml as for MySQL.
Locate the pentaho-solutions/system/dialects/mysql5/audit_sql.xml file.
Copy it into the pentaho-solutions/system directory.