1. sudo user   to  admin
2. Open the /etc/apache2/apache2.conf file.

   $ sudo nano /etc/apache2/apache2.conf
   

   Find the content below.

   ...
   <Directory /var/www/>
           Options Indexes FollowSymLinks
           AllowOverride None
           Require all granted
   </Directory>
   ...
   

   Change the line:

   Options Indexes FollowSymLinks
   

   to:

   Options -Indexes +FollowSymLinks
   

   When finished, it should look like this.

   ...
   <Directory /var/www/>
           Options -Indexes +FollowSymLinks
           AllowOverride None
           Require all granted
   </Directory>
   
   

3. /etc/init.d/apache2 restart

ok work