The latest version of concrete5 adds some new options and mobile capabilities to the YouTube block, and fixes some bugs from 5.4.2, including those with layouts, the Zend Framework, the scrapbook, marketplace item downloading, composer, and more. It is a recommended download for all those running 5.4.2.
Full 5.4.2.1 Release Notes Available Here >
You can download concrete5 5.4.2.1 from the concrete5 downloads page: