Before you do anything else with web development, you should know how to debug your server installation. In this post, I'll assume you're using Apache on Ubuntu, and walk you through a checklist of what to try when something breaks.

Reloading configuration changes

First, any change to the configuration files, whether apache.conf or a VirtualHost file (I'll explain later) MUST be accompanied by service apache2 reload in order to put the new settings into effect.

If you get an error message when you try to run service apache2 reload, check the apache log: tail /var/log/apache2

If it seems like the server settings aren't taking effect, try restarting Apache completely with service apache2 restart.

403 errors

File Permissions

If you get a 403 error in the browser, ever, check the file permissions in your DocumentRoot. You may have to do chmod a+rx /var/www, or whatever. This is not really recommended, but often necessary.

Directory Settings

Next, check the setting in apache2.conf or your virtual host file. (More on this later.) Make sure the pathname is correct, and Require All Granted is specified within the <Directory>...</Directory> block.

One helpful debugging tip is turning on directory indexes, so when browsing a folder, like http://localhost/, and no DirectoryIndex file exists, like index.html or index.php, you get a listing of the files in the site root.

<Directory /var/www/html>
    # other stuff here
  Options +Indexes
</Directory>

My .htaccess file isn't working!

If you want to use .htaccess configs, check your <Directory> rule for the AllowOverride setting. Set to All to enable, None to disable. I recommend NOT using .htaccess files, instead sticking to the virtual host config file, but sometimes you have no other choice.

<Directory /var/www/html>
    # other stuff here
  AllowOverride All
</Directory>