ZohoOAuthException, Can't generating Access token from Grant token

Hello, here my code : PHP SDK for Zoho API

function __construct() {

    $configuration = [
        'client_id'               => '***',
        'client_secret'           => '***',
        'redirect_uri'            => 'www.zohoapis.eu',
        'currentUserEmail'        => '***',
        'token_persistence_path'  => '***',
        'applicationLogFilePath ' => '***',

    ];

    $http = new Client();
    $response = $http->post('https://accounts.zoho.eu/oauth/v2/token', [
        'code'          => '***',
        'redirect_uri'  => '***',
        'client_id'     => '***',
        'client_secret' => '***',
        'grant_type'    => 'authorization_code',
    ]);

    if (isset($response->json['access_token'])) {
        $grantToken = $response->json['access_token'];
    } else {
        dd($response->json['error']);
        die();
    }


    ZCRMRestClient::initialize($configuration);
    $oAuthClient = ZohoOAuth::getClientInstance();
    $oAuthTokens = $oAuthClient->generateAccessToken($grantToken);

}

Return error : Caused by:'Exception while fetching access token from grant token

INFO : I use Token file persistence, because I can't rename tables on my shared host.

Aloso, what's the differente entre grant token or refresh token ?

Thx,