yii2-bootstrap/docs/guide/error.md

Error Handling

Error handling in Yii is different from plain PHP. First of all, all non-fatal errors are converted to exceptions so you can use try-catch to work with these. Second, even fatal errors are rendered in a nice way. In debug mode that means you have a trace and a piece of code where it happened so it takes less time to analyze and fix it.

Using controller action to render errors

Default Yii error page is great for development mode and is OK for production if YII_DEBUG is turned off but you may have an idea how to make it more suitable for your project. An easiest way to customize it is to use controller action for error rendering. In order to do so you need to configure errorHandler component via application config:

return [
    // ...
    'components' => [
        // ...
        'errorHandler' => [
            'errorAction' => 'site/error',
    ],

After it is done in case of error, Yii will launch SiteController::actionError():

public function actionError()
{
    if (\Yii::$app->exception !== null) {
        return $this->render('error', ['exception' => \Yii::$app->exception]);
    }
}

Since most of the time you need to adjust look and feel only, Yii provides ErrorAction class that can be used in controller instead of implementing action yourself:

public function actions()
{
    return [
        'error' => [
            'class' => 'yii\web\ErrorAction',
        ],
    ];
}

After defining actions in SiteController as shown above you can create views/site/error.php. In the view there are three variables available:

• $name: the error name
• $message: the error message
• $exception: the exception being handled