mysql: set default charset to utf8
The problem the server complains about is that it can't find the expected INI section ([mysqld]) to which these settings belong. Ensure you've added those settings to the [mysqld] section, like this:
[mysqld]
character-set-server=utf8
default-collation=utf8_unicode_ci
If there's already such a section there, add your settings to to that section, don't create a duplicate section.
After altering the configuration file, restart the MySQL server.