How to fix error “Could not reliably determine the server’s fully qualified domain name using 127.0.1.1 for ServerName" on apache2

To fix this problem  you need to edit the /etc/apache2/apache2.conf

1. Open the /etc/apache2/apache2.conf file with your text editor.

    #pico /etc/apache2/apache2.conf

2. Add the following line:

    ServerName localhost

3. Restart apache2 server:
    #service apache2 restart
    Restarting web server: apache2 … waiting ..

Now your problem is gone. Enjoy.