src/controllers/TinkoffController.php
public function actionOrderForm()
    {
        if (!$key = \Yii::$app->request->get('key')) {
            throw new Exception('Order not found');
        }

        if (!$order = ShopOrder::find()->where(['key' => $key])->one()) {
            throw new Exception('Order not found');
        }

        return $this->render($this->action->id, [
            'model' => $order,
        ]);
    }
public function actionOrderForm()
    {
        if (!$key = \Yii::$app->request->get('key')) {
            throw new Exception('Order not found');
        }

        if (!$order = ShopOrder::find()->where(['key' => $key])->one()) {
            throw new Exception('Order not found');
        }

        return $this->render($this->action->id, [
            'model' => $order,
        ]);
    }
Payment form

@throws Exception