Your PHP installation appears to be missing the MySQL extension which is required by WordPress
I tried to fix this problem by making sure MySQL server is running.
dpkg --list | grep php5-mysql
Thanks for contributing to the answer.
Nothing worked to solve this issue. Although I faced the same issue. @igor yavych answer was quite useful.
Finally R&D worked and here's the final solution:
In order to deploy PHP applications, you will need to implement the following “PHP-FastCGI” solution to allow nginx to properly handle and serve pages that contain PHP code.
sudo apt-get install php5-cli php5-cgi php5-fpm
Now, install NGINX:
sudo apt-get install nginx
Now configure NGINX then restart NGINX and PHP5-fpm:
service php5-fpm restart /etc/init.d/nginx restart
Issue the following command to install the MySQL server packages and required PHP support for MySQL (You do not have to purge MySQL Server):
sudo apt-get install mysql-server php5-mysql
Finally restart php5-fpm:
service php5-fpm restart
Congratulations! Now it's working!