I'm creating a custom module for Joomla 4, but having problems with namespacing. I've been following the steps here: https://docs.joomla.org/Special:MyLanguage/J4.x:Creating_a_Simple_Module#Namespaces but still having issues.

The module is "mod_jpc_menu_link_display" and all files are in that folder.

The helper file (/helper/mod_jpc_menu_link_display_helper.php) contains:

namespace Joomla\Module\JpcMenuLinkDisplay\Site\Helper;

as well as a class:

class MenuLinkHelper {}

The main module file (mod_jpc_menu_link_display.php) contains:

use Joomla\Module\JpcMenuLinkDisplay\Site\Helper\MenuLinkHelper;
$menuItems = MenuLinkHelper::getItems($params);

And the manifest file (mod_jpc_menu_link_display.xml contains:

    <filename module="mod_jpc_menu_link_display">mod_jpc_menu_link_display.php</filename>

Everything appears proper to me; however, when the module is placed and the front-end is displayed I get a Symfony\Component\ErrorHandler\Error: ClassNotFoundError

Attempted to load class "MenuLinkHelper" from namespace "Joomla\Module\JpcMenuLinkDisplay\Site\Helper".
Did you forget a "use" statement for another namespace?

I've looked this over a bunch of times and I'm not able to find the problem with this.

Any idea why it is not loading the namespace and class properly or giving that error?

1 Answer 1


Joomla uses PSR-4 autoloader. You must follow this convention for builtin autoloading to work. In your case you have to rename the helper file to match the class file, i.e. it should be /Helper/MenuLinkHelper.php.

  • Thanks. I've seen no place (esp. in the Joomla docs) that explains that requirement. Thanks for clearing it up. Works perfectly after making that change. May 2, 2023 at 15:49
  • For documentation on Joomla4-development, I like browsing dionysopoulos.me/book.html May 3, 2023 at 6:28

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