.htaccess ErrorDocument 404 not showing up

First, note that restarting httpd is not necessary for .htaccess files. .htaccess files are specifically for people who don't have root - ie, don't have access to the httpd server config file, and can't restart the server. As you're able to restart the server, you don't need .htaccess files and can use the main server config directly.

Secondly, if .htaccess files are being ignored, you need to check to see that AllowOverride is set correctly. See http://httpd.apache.org/docs/2.4/mod/core.html#allowoverride for details. You need to also ensure that it is set in the correct scope - ie, in the right block in your configuration. Be sure you're NOT editing the one in the block, for example.

Third, if you want to ensure that a .htaccess file is in fact being read, put garbage in it. An invalid line, such as "INVALID LINE HERE", in your .htaccess file, will result in a 500 Server Error when you point your browser at the directory containing that file. If it doesn't, then you don't have AllowOverride configured correctly.

1. Enable Apache mod_rewrite module

   a2enmod rewrite

2. add the following code to /etc/apache2/sites-available/default

   AllowOverride All

3. Restart apache

   /etc/init.d/apache2 restart

If you have tried all of the above, which are all valid and good answers, and your htaccess file is not working or being read change the directive in the apache2.conf file. Under Ubuntu the path is /etc/apache2/apache2.conf

Change the <Directory> directive pointing to your public web pages, where the htaccess file resides. Change from AllowOverride None to AllowOverride All

<Directory /var/www/>
Options Indexes FollowSymLinks
AllowOverride All
Require all granted
</Directory>

I had the same problem and found the answer and explanation on the Ubuntu Ask! forum https://askubuntu.com/questions/421233/enabling-htaccess-file-to-rewrite-path-not-working