Custom 404 Error Page + sh404SEF

-- HikaShop version -- : 4.0.0
-- Joomla version -- : 3.9.12
-- PHP version -- : 7.2

Hello,

My site uses sh404SEF but I have disabled it for Hikashop using the "By Component" setting, leaving it to Joomla router. This solution has been suggested by both extensions for optimal performance. This has mostly been a success.

I am wondering about handling 404 errors & showing an error page. If I test by making up a non-existing URL it just shows the system message heading "Warning" with a message "Page not found: abcdefg"

This is not the sh404SEF error page, nor is it Joomla's typical 404 page with the red title bar & "article not found" or "component not found" message. Is there something happening with HikaShop with it's SEF handling?

Hi Nicolas, thanks for your reply. But it is not the Joomla error page or a custom error page.

Eventually, I will set up a custom error page. But I have not put any error.php file in my template yet, and I can't get the Joomla system one to show. When I make up a page URL that doesn't exist, it should show the "system" error page. Like this:

Hi Nicolas, thanks for looking further.

I did not have an override for the product / show. But I checked it and compared the code, it looks slightly different - here's what mine contained, without any override (strange!):

if(empty($this->element)) {
	if($this->config->get('404_when_product_not_found',1)){
		header($_SERVER["SERVER_PROTOCOL"] . " 404 Not Found", true, 404);
		$app = JFactory::getApplication();
		$app->enqueueMessage(JText::_('PRODUCT_NOT_FOUND'), 'error');
		echo '</div>';
		return;
	}
	$app->enqueueMessage(JText::_('PRODUCT_NOT_FOUND'));
	hikashop_setPageTitle(JText::_('PRODUCT_NOT_FOUND'));
	echo '</div>';
	return;
}