For the warning you should just add ServerName
in your global configuration file.
<VirtualHost 127.0.0.2:80>
ServerName com
DocumentRoot /home/user/projects
</VirtualHost>
For the error you should changer the owner of your website folder like this: chown user_apache.group_apache /home/user/projects -R
(for example in ubuntu/debian chown www-data.www-data /home/user/projects -R
)