I have installed php7, I did the following to solve exactly the same error
sudo apt-get install php7.0-gd
sudo apt-get install php7.0-intl
sudo apt-get install php7.0-xsl
I have installed php7, I did the following to solve exactly the same error
sudo apt-get install php7.0-gd
sudo apt-get install php7.0-intl
sudo apt-get install php7.0-xsl