Download latest release of CardDav plugin.
https://plugins.roundcube.net/#/packages/roundcube/carddav
https://packagist.org/packages/roundcube/carddav
https://github.com/blind-coder/rcmcarddav/releases
https://github.com/blind-coder/rcmcarddav/releases/download/v3.0.3/carddav-3.0.3.zip
cd /opt/www/roundcubemail/plugins/ wget -c https://github.com/blind-coder/rcmcarddav/releases/download/v3.0.3/carddav-3.0.3.zip unzip carddav-3.0.3.zip cd carddav cp config.inc.php.dist config.inc.php
vim /opt/www/roundcubemail/config/config.inc.php
// PLUGINS
$config['plugins'] = array('managesieve', 'password','carddav');