As of eZ Publish 5.2, if you will use eZ Publish on legacy mode the Zetacomponents configuration must be updated.
For that you will need to install composer, which you can do by running one of the following command from you eZ Publish root folder:
If you have curl installed:
curl -sS https://getcomposer.org/installer | php
If you don't have curl installed:
php -r "eval('?>'.file_get_contents('https://getcomposer.org/installer'));"
After composer installed run the following command from the the ezpublish_legacy/ folder folder:
php composer.phar install