We have a special situation where we include Joomla from within Yii 2, which worked fine with Joomla 3, but Joomla 4.2 is so far giving us some problems. The latest issue is:

Error: Class "Joomla\Plugin\Actionlog\Joomla\Extension\Joomla" not found

Some forum threads recommend to delete autoload cache in administrator/cache/ folder, but we have no such file.

Our current bootstrapping code looks like this:

    // Include defines.php and framework.php omitted
    $container = \Joomla\CMS\Factory::getContainer();
    $container->alias(\Joomla\Session\SessionInterface::class, 'session.cli');
    $app = \Joomla\CMS\Factory::getContainer()->get(\Joomla\CMS\Application\SiteApplication::class);
    \Joomla\CMS\Factory::$application = $app;
    $app->triggerEvent('onAfterInitialise', []);

Note that we need to use SiteAppplication to get getDocument() to work properly.

It fails on PluginHelper::importPlugin().

Any tips? Should we perhaps hack the Yii 2 composer.json file to point the namespace correctly? Or is there a simple command missing to setup Joomla correctly? Another solution to maybe add a new spl_autoload_register.

This error appears both locally with a git clone joomla-cms, and on our live server.

Edit: Adding this PSR-4 instruction to our Yii 2 composer.json did not work, it seems

 80         "psr-4": {                                                                                                                                                                         
 81             "Joomla\\Plugin\\": "joomla-src/plugin"                                                                                                                                        
 82         }                                                                                                                                                                                  

Maybe the autoloaders inside Joomla are not PSR-4 compliant?

Edit 2: No way to programmatically generate the autoloader psr4 file in cache folder? We have a copy from live site, but I need to figure out how to load it properly.

Trying this:

    require_once JPATH_LIBRARIES . '/namespacemap.php';
    $extensionPsr4Loader = new \JNamespacePsr4Map();

1 Answer 1


That final piece of code seems to have done it.

require_once JPATH_LIBRARIES . '/namespacemap.php';
$extensionPsr4Loader = new \JNamespacePsr4Map();

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