While learning Facebook SDK for PHP I overlooked one of system requirements preventing my code from running on my host. That is The mbstring extension. Facebook SDK for PHP's system requirements Check if mbstring is enabled root@ubuntu001:~# php -a Interactive mode enabled php > echo extension_loaded('mbstring'); php >exit root@ubuntu001:~# apt-cache search php7 | grep mbstring php7.0-mbstring - MBSTRING module for PHP root@ubuntu001:~# Install php7.0-mbstring root@ubuntu001:~# apt-get install php7.0-mbstring Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: fontconfig-config fonts-dejavu-core libfontconfig1 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libmcrypt4 libtiff5 libvpx3 libxpm4 Use 'apt autoremove' to remove them. The following additional packages will be installed: libapache2-mod-php7.0 php7.0-cli ph...