Souke/backend/web/main-local.php

<?php

$config = [
    'components' => [
        'request' => [
            // !!! insert a secret key in the following (if it is empty) - this is required by cookie validation
            'cookieValidationKey' => '97ab1b4e420025edccf116eafc92ffd6',
        ],
    ],
];

if (!YII_ENV_TEST) {
    // configuration adjustments for 'dev' environment
    $config['bootstrap'][] = 'debug';
    $config['modules']['debug'] = 'yii\debug\Module';

    $config['bootstrap'][] = 'gii';
    $config['modules']['gii'] = 'yii\gii\Module';
}

return $config;