Fatal error: Uncaught Error: Call to undefined function WP_Optimize() in /htdocs/wp-content/plugins/wp-optimize/cache/file-based-page-cache-functions.php:165 Stack trace: #0 [internal function]: wpo_cache('<!DOCTYPE html>...', 9) #1 /htdocs/wp-includes/functions.php(4673): ob_end_flush() #2 /htdocs/wp-includes/class-wp-hook.php(287): wp_ob_end_flush_all('') #3 /htdocs/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array) #4 /htdocs/wp-includes/plugin.php(478): WP_Hook->do_action(Array) #5 /htdocs/wp-includes/load.php(1007): do_action('shutdown') #6 [internal function]: shutdown_action_hook() #7 {main} thrown in /htdocs/wp-content/plugins/wp-optimize/cache/file-based-page-cache-functions.php on line 165