Requests_Cookie_Jar not found

Hi,

We were getting a PHP FATAL error given below which was preventing admin_area to load with 500 error. Though we used a work around by commenting lines on 589 in class-requests.php after that admin_area started to work but we are not able to install plugin with error which is mentioned on 2nd point:

1- [29-Jun-2017 11:04:36 UTC] PHP Fatal error: Uncaught Error: Class ‘Requests_Cookie_Jar’ not found in wp-includes/class-requests.php:589
Stack trace:
#0 /var/www/html/wp-includes/class-requests.php(363): Requests::set_defaults(‘https://api.wor…’, Array, Array, ‘POST’, Array)
#1 /var/www/html/wp-includes/class-http.php(371): Requests::request(‘https://api.wor…’, Array, Array, ‘POST’, Array)
#2 /var/www/html/wp-includes/class-http.php(594): WP_Http->request(‘https://api.wor…’, Array)
#3 /var/www/html/wp-includes/http.php(187): WP_Http->post(‘https://api.wor…’, Array)
#4 /var/www/html/wp-admin/includes/plugin-install.php(155): wp_remote_post(‘https://api.wor…’, Array)
#5 /var/www/html/wp-admin/includes/class-wp-plugin-install-list-table.php(207): plugins_api(‘query_plugins’, Object(stdClass))
#6 /var/www/html/wp-admin/plugin-install.php(39): WP_Plugin_Install_List_Table->prepare_items()
#7 {main}

2: http://prntscr.com/fpjp3g

The lines we commented of class-requests which solved admin area problem are : http://prntscr.com/fpjpww

Please let me know if any more info is required ?

Regards.
Shahzaib