使用刷新令牌异常{"error" :"invalid_grant"； }'

我已经成功构建了一个获取访问和刷新令牌的应用程序.

I've successfully built an application that fetches an access and refresh token.

在我的脚本中，我检查访问令牌是否有效，如果无效，则使用刷新令牌来获取访问权限$client->refreshToken($refreshToken);

In my script I check if the access token is valid and if not I then use the refresh token to gain access $client->refreshToken($refreshToken);

完整的代码

    $refreshToken = '<REFRESH_TOKEN>';

    $client_id = '<CLIENT_ID>';
    $client_secret = '<CLIENT_SECRET>';

    // Setup infomation
    $client = new Google_Client();
    $client->setClientId($client_id);
    $client->setClientSecret($client_secret);
    $client->setAccessType("offline");
    $client->addScope("https://mail.google.com/");

    // If access token is not valid use refresh token
    if($client->isAccessTokenExpired()) {

        // Use refresh token
        $client->refreshToken($refreshToken);

    } else {

        // Use access token
        echo $client->setAccessToken($accessToken);

    }

但是，当尝试使用刷新令牌时，我会感到很遗憾:

However when trying to use the refresh token I get an excpetion :

Fatal error: Uncaught exception 'Google_Auth_Exception' with message 'Error refreshing the OAuth2 token, message: '{ "error" : "invalid_grant" }''