Plugin RegisterUrlRulesEvent - cannot find Controller aciton -> 404
Found a Solution
Context:
When I created my plugin-frame through https://pluginfactory.io the DefaultController was still a thing -&gt; routing to /pluginname/default-controller-action-name worked as it defaulted to search in the... default-controller. But it seems that is no more, so what I had to do instead to get it to find the action is add a section referring to the controller.
this is the new/fixed code:
// ./src/Expedweather.php::init
$map_page = 'data\/&lt;range:\w+&gt;\/&lt;peak:\w+&gt;\/&lt;view:\w+&gt;\/&lt;parameter:\w+&gt;';
$event-&gt;rules[$map_page] = 'expedweather/default/forecast-panel'; // &lt;-- changed!!
// ./src/controllers/DefaultController
protected $allowAnonymous = ['index', 'forecast-panel'];
public function actionForecastPanel() {...}

The only row that changed is the $event-&gt;rules one which now has /default/ before the action -&gt; this refers to the DefaultController.