No PostgreSQL clusters exist; see "man pg_createcluster"

Solution :

Run commands :

dpkg-reconfigure locales

pg_createcluster 9.3 main --start
or
pg_createcluster 9.4 main --start
or
pg_createcluster 9.5 main --start

(depends on your postgresql version.)

Ubuntu Apache php error : Class 'NumberFormatter' not found

Solution :

Install Package :

apt-get install php5-intl
or
apt-get install php-intl

Make sure intl.so file is generated and it is defined as an extension in .ini file.