Fatal error: Out of memory (allocated 20971520) (tried to allocate 28672 bytes) in C:\xampp\htdocs\w101\wp-includes\pluggable.php on line 1747

Fatal error: Uncaught Error: Call to undefined function is_user_logged_in() in C:\xampp\htdocs\w101\wp-content\plugins\wp-fastest-cache\inc\cache.php:665 Stack trace: #0 [internal function]: WpFastestCacheCreateCache->callback('<br />\n<b>Fatal...', 9) #1 C:\xampp\htdocs\w101\wp-includes\functions.php(4217): ob_end_flush() #2 C:\xampp\htdocs\w101\wp-includes\class-wp-hook.php(286): wp_ob_end_flush_all('') #3 C:\xampp\htdocs\w101\wp-includes\class-wp-hook.php(310): WP_Hook->apply_filters('', Array) #4 C:\xampp\htdocs\w101\wp-includes\plugin.php(465): WP_Hook->do_action(Array) #5 C:\xampp\htdocs\w101\wp-includes\load.php(788): do_action('shutdown') #6 [internal function]: shutdown_action_hook() #7 {main} thrown in C:\xampp\htdocs\w101\wp-content\plugins\wp-fastest-cache\inc\cache.php on line 665