I'm trying to authenticate a user via Tumblr PHP API.
I'm getting this error
Fatal error: Uncaught exception 'GuzzleHttp\Exception\RequestException' with message 'cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)'
When visiting the suggested site this is the explanation of error 60
CURLE_SSL_CACERT (60)
Peer certificate cannot be authenticated with known CA certificates.
I found a similar issue here, but how do I fix mine? Is it the same?
This is the code I'm trying to use
require_once('vendor/autoload.php');
$consumerKey = 'XXX';
$consumerSecret = 'YYY';
$client = new Tumblr\API\Client($consumerKey, $consumerSecret);
$requestHandler = $client->getRequestHandler();
$requestHandler->setBaseUrl('https://www.tumblr.com/');
// If we are visiting the first time
if (!$_GET['oauth_verifier']) {
    // grab the oauth token
    $resp = $requestHandler->request('POST', 'oauth/request_token', array());
    $out = $result = $resp->body;
    $data = array();
    parse_str($out, $data);
    // tell the user where to go
    echo '<a href="https://www.tumblr.com/oauth/authorize?oauth_token=' . $data['oauth_token'].'"> GO </a>';
    $_SESSION['t']=$data['oauth_token'];
    $_SESSION['s']=$data['oauth_token_secret'];
} else {
    $verifier = $_GET['oauth_verifier'];
    // use the stored tokens
    $client->setToken($_SESSION['t'], $_SESSION['s']);
    // to grab the access tokens
    $resp = $requestHandler->request('POST', 'oauth/access_token', array('oauth_verifier' => $verifier));
    $out = $result = $resp->body;
    $data = array();
    parse_str($out, $data);
    // and print out our new keys we got back
    $token = $data['oauth_token'];
    $secret = $data['oauth_token_secret'];
    echo "token: " . $token . "<br/>secret: " . $secret;
    // and prove we're in the money
    $client = new Tumblr\API\Client($consumerKey, $consumerSecret, $token, $secret);
    $info = $client->getUserInfo();
    echo "<br/><br/>congrats " . $info->user->name . "!";
}
