Yii2, error occurs while throwing NotFoundException

Question

I have a simple code that is running on beforeAction event of my application:

'on beforeAction' => function ($event) {
    throw new \yii\web\NotFoundHttpException('The requested page does not exist.');
},

I expect it to simply show 404 page of my application, but it throws following error:

An Error occurred while handling another error:
exception 'yii\web\NotFoundHttpException' with message 'The requested page does not exist.' in /home/files/www/ucms/config/frontend/config.php:9
Stack trace:
0 [internal function]: {closure}(Object(yii\base\ActionEvent))
1 /home/files/www/ucms/vendor/yiisoft/yii2/base/Component.php(541): call_user_func(Object(Closure), Object(yii\base\ActionEvent))
2 /home/files/www/ucms/vendor/yiisoft/yii2/base/Module.php(607): yii\base\Component->trigger('beforeAction', Object(yii\base\ActionEvent))
3 /home/files/www/ucms/vendor/yiisoft/yii2/base/Controller.php(139): yii\base\Module->beforeAction(Object(yii\web\ErrorAction))
4 /home/files/www/ucms/vendor/yiisoft/yii2/base/Module.php(455): yii\base\Controller->runAction('error', Array)
5 /home/files/www/ucms/vendor/yiisoft/yii2/web/ErrorHandler.php(85): yii\base\Module->runAction('site/error')
6 /home/files/www/ucms/vendor/yiisoft/yii2/base/ErrorHandler.php(109): yii\web\ErrorHandler->renderException(Object(yii\web\NotFoundHttpException))
7 [internal function]: yii\base\ErrorHandler->handleException(Object(yii\web\NotFoundHttpException))
8 {main}
Previous exception:
exception 'yii\web\NotFoundHttpException' with message 'The requested page does not exist.' in /home/files/www/ucms/config/frontend/config.php:9
Stack trace:
0 [internal function]: {closure}(Object(yii\base\ActionEvent))
1 /home/files/www/ucms/vendor/yiisoft/yii2/base/Component.php(541): call_user_func(Object(Closure), Object(yii\base\ActionEvent))
2 /home/files/www/ucms/vendor/yiisoft/yii2/base/Module.php(607): yii\base\Component->trigger('beforeAction', Object(yii\base\ActionEvent))
3 /home/files/www/ucms/vendor/yiisoft/yii2/base/Controller.php(139): yii\base\Module->beforeAction(Object(yii\base\InlineAction))
4 /home/files/www/ucms/vendor/yiisoft/yii2/base/Module.php(455): yii\base\Controller->runAction('', Array)
5 /home/files/www/ucms/vendor/yiisoft/yii2/web/Application.php(84): yii\base\Module->runAction('', Array)
6 /home/files/www/ucms/vendor/yiisoft/yii2/base/Application.php(375): yii\web\Application->handleRequest(Object(yii\web\Request))
7 /home/files/www/ucms/web/index.php(17): yii\base\Application->run()
8 {main}

Answer 1

Problem in ErrorHandler.php file on 85 line:

$result = Yii::$app->runAction($this->errorAction);

When ErrorHandler try run ErrorAction, NotFoundHttpException triggered again and ErrorHandler just show error message without render.

Solution:

public function beforeAction($action)
{
    if(!$action instanceof \yii\web\ErrorAction) {
        throw new \yii\web\NotFoundHttpException('The requested page does not exist.');
    }

    return parent::beforeAction($action);
}

---

Previous Answer: On production server also need setup right environments settings in your index.php file:

defined('YII_DEBUG') or define('YII_DEBUG', false);
defined('YII_ENV') or define('YII_ENV', 'prod');