Json connection returning null and error-free in the json_errors variable

Question

Code being used in a php in the /root folder:

<?php

$jsoncontent = file_get_contents('https://xx.xxx.xx.xxx/v1/API_operation');
$jsoncontent = utf8_encode($jsoncontent);
$data = json_decode($jsoncontent,true);
echo $data;

$json_errors = array(
    JSON_ERROR_NONE => 'No error has occurred',
    JSON_ERROR_DEPTH => 'The maximum stack depth has been exceeded',
    JSON_ERROR_CTRL_CHAR => 'Control character error, possibly incorrectly encoded',
    JSON_ERROR_SYNTAX => 'Syntax error',
);
 echo 'Last error : ', $json_errors[json_last_error()], PHP_EOL, PHP_EOL;

The result is Last error : No error has occurred, but it does not display any component/object of the referent link, what can I do?

When I do var_dump($http_response_header); receiving:

array(9) { 
    [0]=> string(22) "HTTP/1.1 404 Not Found" 
    [1]=> string(25) "Server: Apache-Coyote/1.1" 
    [2]=> string(103) "X-Powered-By: Servlet 2.4; JBoss-4.2.3.GA (build: SVNTag=JBoss_4_2_3_GA date=200807181439)/JBossWeb-2.0" 
    [3]=> string(35) "Date: Sat, 23 May 2015 05:24:02 GMT" 
    [4]=> string(20) "Accept-Ranges: bytes" 
    [5]=> string(31) "Server: Restlet-Framework/2.0.7" 
    [6]=> string(37) "Content-Type: text/html;charset=UTF-8" 
    [7]=> string(19) "Content-Length: 439" 
    [8]=> string(17) "Connection: close"
}