Как исправить ошибку от Yii2: Not instantiable – yii\di\NotInstantiableException Failed to instantiate component or class "yii\grid\.."

При замене оригинального класса дочерним получаю сообщение об ошибке:

Not instantiable – yii\di\NotInstantiableException
Failed to instantiate component or class "yii\grid\MyActionColumn".
Caused by: ReflectionException
Class "yii\grid\MyActionColumn" does not exist 

Cтрочки кода из views/contact/index.php, которые вызывают ошибку:

    <?= GridView::widget([
        'dataProvider' => $dataProvider,
        'filterModel' => $searchModel,
        'emptyText' => 'По указанным параметрам сотрудник не найден.',
        'columns' => [
            ['class' => 'yii\grid\SerialColumn'],

            'last_name',
            'first_name',
            'middle_name',
            'internal_phone',
            'mobile_phone',
            'email_address:email',

            ['class' => 'yii\grid\MyActionColumn',
                'template' => '{view} {update} {delete}',
                ],
        ],
    ]); ?>

controllers/MyActionColumn.php:

<?php
namespace yii\grid;
    
use Yii;

class MyActionColumn extends ActionColumn
{

}

composer.json:

{
    "name": "yiisoft/yii2-app-basic",
    "description": "Yii 2 Basic Project Template",
    "keywords": ["yii2", "framework", "basic", "project template"],
    "homepage": "http://www.yiiframework.com/",
    "type": "project",
    "license": "BSD-3-Clause",
    "support": {
        "issues": "https://github.com/yiisoft/yii2/issues?state=open",
        "forum": "http://www.yiiframework.com/forum/",
        "wiki": "http://www.yiiframework.com/wiki/",
        "irc": "irc://irc.freenode.net/yii",
        "source": "https://github.com/yiisoft/yii2"
    },
    "minimum-stability": "stable",
    "require": {
        "php": ">=5.6.0",
        "yiisoft/yii2": "~2.0.14",
        "yiisoft/yii2-bootstrap4": "~2.0.0",
        "yiisoft/yii2-swiftmailer": "~2.0.0 || ~2.1.0"
    },
    "require-dev": {
        "yiisoft/yii2-debug": "~2.1.0",
        "yiisoft/yii2-gii": "~2.2.0",
        "yiisoft/yii2-faker": "~2.0.0",
        "codeception/codeception": "^4.0",
        "codeception/verify": "~0.5.0 || ~1.1.0",
        "codeception/specify": "~0.4.6",
        "symfony/browser-kit": ">=2.7 <=4.2.4",
        "codeception/module-filesystem": "^1.0.0",
        "codeception/module-yii2": "^1.0.0",
        "codeception/module-asserts": "^1.0.0"
    },
    "config": {
        "process-timeout": 1800,
        "fxp-asset": {
            "enabled": false
        }
    },
    "scripts": {
        "post-install-cmd": [
            "yii\\composer\\Installer::postInstall"
        ],
        "post-create-project-cmd": [
            "yii\\composer\\Installer::postCreateProject",
            "yii\\composer\\Installer::postInstall"
        ]
    },
    "extra": {
        "yii\\composer\\Installer::postCreateProject": {
            "setPermission": [
                {
                    "runtime": "0777",
                    "web/assets": "0777",
                    "yii": "0755"
                }
            ]
        },
        "yii\\composer\\Installer::postInstall": {
            "generateCookieValidationKey": [
                "config/web.php"
            ]
        }
    },
    "repositories": [
        {
            "type": "composer",
            "url": "https://asset-packagist.org"
        }
    ]
} 

в чем может быть дело?