Error message

• Warning: file_get_contents(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed in include() (line 7 of /opt/jres/www/www.jres.org/sites/default/files/programme/video.php).
• Warning: file_get_contents(): Failed to enable crypto in include() (line 7 of /opt/jres/www/www.jres.org/sites/default/files/programme/video.php).
• Warning: file_get_contents(https://conf-ng.jres.org/2017/rest/articles.xml?format=json): failed to open stream: operation failed in include() (line 7 of /opt/jres/www/www.jres.org/sites/default/files/programme/video.php).