“Could not reliably determine the server’s fully qualified domain name, using … for ServerName"

You might probably faced the same following error while you were restarting the Apache server on Ubuntu.

$ sudo /etc/init.d/apache2 restart
* Restarting web server apache2            
apache2: Could not reliably determine the server’s 
fully qualified domain name, using 127.0.1.1 for 
ServerName
… waiting apache2: Could not reliably determine the
 server’s fully qualified domain name, using
127.0.1.1 for ServerName

To fix that problem, you need to edit the httpd.conf file. Open the terminal and type,

$ sudo gedit /etc/apache2/httpd.conf

By default httpd.conf file will be blank. Now, simply add the following line to the file.

ServerName localhost

Save the file and exit from gEdit.

Finally restart the server.

$ sudo /etc/init.d/apache2 restart