Downgrade from php7 to php5.6 on Ubuntu 16.04

Downgrade from php7 to php5.6 on Ubuntu 16.04

Установка php5.6:

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-xdebug libapache2-mod-php5.6 libapache2-mod-php7.0

Переключение на php5.6:

sudo a2dismod php7.0 ; sudo a2enmod php5.6
sudo ln -sfn /usr/bin/php5.6 /etc/alternatives/php
service apache2 restart

Переключение на php7:

sudo a2dismod php5.6 ; sudo a2enmod php7.0
sudo ln -sfn /usr/bin/php5.6 /etc/alternatives/php
service apache2 restart

Взято отсюда