How to fix Apache - "Could not reliably determine the server's fully qualified domain name...

To stop this message being generated when you start Apache, you need to give it a value for ServerName. Follow the steps below to do this:

At the Pi command line, edit the Apache configuration file name.

sudo nano /etc/apache2/conf.d/name

Add the line

ServerName localhost

noting the capitalisation, then save and exit. To make these changes live, you need to restart Apache so that it reloads the new configuration.

sudo /etc/init.d/apache2 reload