Creating a Custom 404 Error Page

From Joomla! Documentation

This tutorial will show you how to create a custom 404 error page for use in your Joomla Webssite.

Four Steps to Creating a Custom 404 Error Page

  1. Create an Uncategorized '404' Article
    Create an 'uncategorized' article in Joomla! to serve as your 404 Page. Include some text such as Sorry, we could not find the page you were looking for... and if necessary, also any useful navigational links. For example, you may wish to add a link back to your site's home page.
  2. Create and copy a link to that new 404 Article.
    Create a menu item which links to the new 404 Article and 'apply' your changes. Then copy the URL information (index.php?optio...), set the menu item as 'unpublished' and close out of the menu editing page. You may want to paste the copied URL into Notepad or somewhere accessible for the time-being.
  3. Copy error.php to your Template's Directory
    In your Joomla! installation copy the file error.php from the templates/system directory, to your Template directory. For example, if I was using a template named 'Cleancloud' I would copy the error.php file to the templates/cleancloud directory.
  4. Modify error.php to Redirect 404 Errors to your 404 Article
    Edit the error.php file as follows, adding the code below immediately under the 'restricted access' line:
if (($this->error->code) == '404') {
header('Location: /index.php?option=com_content&view=article&id=75');

If you are using Joomla 1.6, 1.7 and 2.5, use this detection code instead:

if (($this->error->getCode()) == '404') {

Replace the location information (index.php?option..) with the URL from the menu item you created.

Additional Steps Toward a Better Custom 404 Error Page

More Custom Error Page Information