Hi, I am having the same issue.
$ wp plugin list
PHP Notice: Undefined index: HTTP_HOST in /home/chd/sites/main/web/app/plugins/wp-fastest-cache/inc/cache.php on line 321
Notice: Undefined index: HTTP_HOST in /home/chd/sites/main/web/app/plugins/wp-fastest-cache/inc/cache.php on line 321
