As per the title, how can we catch a RouteNotFoundException? For time constraints, instead of creating a custom component we opted for some hand-waving, and decided to display custom content at non-routed URL's, and it's working, but we would like to catch the exception. I tried acting on error.php and index.php, but to no avail.

1 Answer 1


In J4 exceptions can be handled by system plugins with onError event:

use Joomla\CMS\Event\ErrorEvent;
use Joomla\CMS\Plugin\CMSPlugin;
use Joomla\CMS\Router\Exception\RouteNotFoundException;

class PlgSystemExample extends CMSPlugin
    public function onError(ErrorEvent $event)
        if ($event->getError() instanceof RouteNotFoundException)
            // Handle the exception.
  • Thank you! Would this need to be added into error.php or index.php ? Jun 7, 2022 at 14:24
  • No, it's a plugin.
    – Sharky
    Jun 8, 2022 at 7:54

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