[14-Jan-2018 09:57:36 UTC] PHP Fatal error: Uncaught Error: Call to undefined function curl_init() in /var/www/html/wp-content/plugins/kraken-image-optimizer/lib/Kraken.php:65
Stack trace:
#0 /var/www/html/wp-content/plugins/kraken-image-optimizer/lib/Kraken.php(50): Kraken->request(Array, 'https://api.kra...', 'upload')
#1 /var/www/html/wp-content/plugins/kraken-image-optimizer/kraken.php(1171): Kraken->upload(Array)
#2 /var/www/html/wp-content/plugins/kraken-image-optimizer/kraken.php(1273): Wp_Kraken->optimize_image('/var/www/html/w...', 'lossy')
#3 /var/www/html/wp-includes/class-wp-hook.php(288): Wp_Kraken->optimize_thumbnails(Array)
#4 /var/www/html/wp-includes/plugin.php(203): WP_Hook->apply_filters(Array, Array)
#5 /var/www/html/wp-admin/includes/image.php(293): apply_filters('wp_generate_att...', Array, 11506)
#6 /var/www/html/wp-admin/includes/media.php(384): wp_generate_attachment_metadata(11506, '/var/www/html/w...')
#7 /var/www/html/wp-admin/includes/ajax-actions.php(2113): media_handle_upload('async-upload', '11505', Array)
#8 /var/www/ht in /var/www/html/wp-content/plugins/kraken-image-optimizer/lib/Kraken.php on line 65
This is the error I got in the log. Curl is installed and working though.