Customizing 404 Error Page in Gantry 5
404 error page will get configurations from Base outline, however you could add more information or customize 404 page by following -
- Log in to Joomla! Administrator if you haven't already.
- Access the template admin by navigating to Components -> Gantry 5 Themes -> Default Theme in the left menu.
- Switch to Error
- Click on Layout tab and customize as you need.