On installing Moodle on Ubuntu 16.04 server, i got following error

Error: database driver problem detected

The site administrator should verify server configuration

PHP has not been properly configured with the PGSQL extension so that it can communicate with PostgreSQL. Please check your php.ini file or recompile PHP.

Fixed by installing php7.0-pgsql package.

apt -y install php7.0-pgsql
service apache2 restart