Manual Switching
From PHP 5.6 => PHP 7.1
Default PHP 5.6 is set on your system and you need to switch to PHP 7.1.
Apache:
$ sudo a2dismod php5.6
$ sudo a2enmod php7.1
$ sudo service apache2 restart
Command Line:
$ sudo update-alternatives --set php /usr/bin/php7.1
$ sudo update-alternatives --set phar /usr/bin/phar7.1
$ sudo update-alternatives --set phar.phar /usr/bin/phar.phar7.1
From PHP 7.1 => PHP 5.6
Default PHP 7.1 is set on your system and you need to switch to PHP 5.6.
Apache:
$ sudo a2dismod php7.1
$ sudo a2enmod php5.6
$ sudo service apache2 restart