I am trying to setup webserver with PHP 7 RC3 + Nginx on Ubuntu 14.04 (for test purposes).
I installed Ubuntu in Vagrant using
First, check if your php.ini has the extension enabled "php_pdo_mysql" and "php_mysqli" and the path of "extension_dir" is correct. If you need one of above configuration, then, you must restart the php-fpm to apply the changes.
In my case (where i am using the Windows OS in the company, i really prefer OSX or Linux), i solved the problem putting this values in the php.ini:
; ...
extension_dir = "ext"
; ...
extension=php_mysqli.dll
extension=php_pdo_mysql.dll
; ...
I hope this helps.