accounts/environments/prod/api/config/main-local.php

<?php
return [
    'components' => [
        'request' => [
            // !!! insert a secret key in the following (if it is empty) - this is required by cookie validation
            'cookieValidationKey' => '',
        ],
        'reCaptcha' => [
            'public' => '',
            'secret' => '',
        ],
    ],
];