php - curl 呼び出しを理解する - curl_exec が false を返す

Question

以下のコードを書きましたが、curl 応答を取得できません。以下のデバッグ情報について言及しました。

なぜこの問題のcurl_execがfalseを返すのかを調べるのを手伝ってもらえますか.

$jwtToken       = getToken();
$service_url    = "https://example.com/api/Demo/GetProjectAttributes/1484";

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $service_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt( $ch, CURLOPT_HTTPHEADER, array (
                "Content-Type: application/x-www-form-urlencoded",
                "Authorization: Bearer $jwtToken"
) );

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_CAINFO, getcwd() . "/mycert.crt");

$response = curl_exec($ch);

if ($response === false ) {
    $info = curl_getinfo($ch);
    echo '<pre>';
    die('error occured during curl exec. Additioanl info: ' . var_export($info));
    curl_close($ch);
}

カールが失敗し、以下の情報が表示されます:

array (
  'url' => 'https://example.com/api/Demo/GetProjectAttributes/1484',
  'content_type' => NULL,
  'http_code' => 0,
  'header_size' => 0,
  'request_size' => 0,
  'filetime' => -1,
  'ssl_verify_result' => 0,
  'redirect_count' => 0,
  'total_time' => 0.57699999999999996,
  'namelookup_time' => 0,
  'connect_time' => 0.28100000000000003,
  'pretransfer_time' => 0,
  'size_upload' => 0,
  'size_download' => 0,
  'speed_download' => 0,
  'speed_upload' => 0,
  'download_content_length' => -1,
  'upload_content_length' => -1,
  'starttransfer_time' => 0,
  'redirect_time' => 0,
  'redirect_url' => '',
  'primary_ip' => '104.209.135.21',
  'certinfo' => 
  array (
  ),
  'primary_port' => 443,
  'local_ip' => '192.168.1.4',
  'local_port' => 56491,
)