致命错误：Class'Requests_Cookie'

Question

Problem in running site http://bfestaging.netai.net/. When I run the site, it shows:

Fatal error: Class 'Requests_Cookie' not found in /home/a5583458/public_html/wp-includes/Requests/Cookie/Jar.php on line 171.

$cookies = Requests_Cookie::parse_from_headers($return->headers, $url);