Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires roundcube/roundcubemail dev-develop as 1.99, found roundcube/roundcubemail[dev-master] but it does not match the constraint. Problem 2 - roundcube/carddav[v4.4.1, ..., v4.x-dev, v5.0.0-beta1] require roundcube/plugin-installer ^0.3.0 -> satisfiable by roundcube/plugin-installer[0.3.99]. - roundcube/carddav[v4.0.0-alpha1, ..., v4.4.0] require roundcube/plugin-installer * -> satisfiable by roundcube/plugin-installer[0.3.99]. - roundcube/carddav[v5.0.0, ..., v5.1.0] require php >=7.4.0 -> your php version (7.3.33) does not satisfy that requirement. - roundcube/plugin-installer 0.3.99 requires roundcube/roundcubemail * -> found roundcube/roundcubemail[dev-master] but it conflicts with your root composer.json require (dev-develop as 1.99). - Root composer.json requires roundcube/carddav ^4 || ^5 -> satisfiable by roundcube/carddav[v4.0.0-alpha1, ..., v4.x-dev, v5.0.0-beta1, v5.0.0, v5.0.1, v5.1.0].