Fatal error: Uncaught Error: Call to undefined function is_plugin_active() in /home/aizu330/pub/interactivebrokers.work/wp/wp-content/plugins/rich-table-of-content/functions.php:519 Stack trace: #0 /home/aizu330/pub/interactivebrokers.work/wp/wp-content/plugins/rich-table-of-content/functions.php(698): rtoc_get_index('<h2 id="rtoc-1"...') #1 /home/aizu330/pub/interactivebrokers.work/wp/wp-includes/class-wp-hook.php(324): rtoc_switch_mokuji('<h2 id="rtoc-1"...') #2 /home/aizu330/pub/interactivebrokers.work/wp/wp-includes/plugin.php(205): WP_Hook->apply_filters('<h2>\xE5\x8F\xA3\xE5\xBA\xA7\xE7\x95\xAA\xE5\x8F...', Array) #3 /home/aizu330/pub/interactivebrokers.work/wp/wp-includes/formatting.php(3965): apply_filters('the_content', '\r\n<h2>\xE5\x8F\xA3\xE5\xBA\xA7\xE7\x95\xAA...') #4 /home/aizu330/pub/interactivebrokers.work/wp/wp-includes/class-wp-hook.php(324): wp_trim_excerpt('\r\n<h2>\xE5\x8F\xA3\xE5\xBA\xA7\xE7\x95\xAA...', Object(WP_Post)) #5 /home/aizu330/pub/interactivebrokers.work/wp/wp-includes/plugin.php(205): WP in /home/aizu330/pub/interactivebrokers.work/wp/wp-content/plugins/rich-table-of-content/functions.php on line 519