Hi guys, if someone is having the same issue here is the way in how to fix it
Using ( nano, vi or gedit ) open the following file.
sudo gedit /etc/php/7.1/apache2/php.ini
and remove the ( ; ) at the begging of the options shown below
opcache.enable=1
opcache.enable_cli=1
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=10000
opcache.memory_consumption=128
opcache.save_comments=1
opcache.revalidate_freq=1
Then restart apache and issue is gone
sudo systemctl restart apache2.service