server error 500 codeigniter

I checked the php version which was 7. copy angka 1 sampai 500 0 xx so I downgraded to php 5 6 xx and used the following steps to get it working for me sudo a2dismod proxy_fcgi proxy; sudo service apache2 restart sudo add-apt-repository ppa:ondrej/php sudo apt-get update sudo apt-get install php7 0 php5 6 php5 6-mysql php-gettext php5 6-mbstring php-mbstring php7 0