DSN (write): NOT OK(SQLSTATE[HY000] [2002] No such file or directory) .

This is what you see when you try to configure a RoundCube installation on a virtual host within webstation on a Synology NAS using MariaDB 10 as a backend database (maybe 5 as well, as I’m not using that).

The solution is to modify the PHP profile you created for RoundCube (or if you didn’t create a specific one maybe do so now in order to avoid issues with other virtual hosts on the platform).

On the advanced settings window of your PHP profile, choose the ‘core’ tab and modify the below two settings in order to get your RoundCube installation connected to your backend database:

• mysqli.default_socket – /run/mysqld/mysqld10.sock
• pdo_mysql.default.socket – /run/mysqld/mysqld10.sock