Warning: Use of undefined constant ABSPATH - assumed 'ABSPATH' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\wp-content\plugins\wp-timelines\timeline.php on line 19

Warning: include_once(ABSPATHwp-admin/includes/plugin.php): failed to open stream: No such file or directory in C:\xampp\htdocs\wp-content\plugins\wp-timelines\timeline.php on line 19

Warning: include_once(): Failed opening 'ABSPATHwp-admin/includes/plugin.php' for inclusion (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\wp-content\plugins\wp-timelines\timeline.php on line 19

Fatal error: Uncaught Error: Call to undefined function is_plugin_active() in C:\xampp\htdocs\wp-content\plugins\wp-timelines\timeline.php:20 Stack trace: #0 {main} thrown in C:\xampp\htdocs\wp-content\plugins\wp-timelines\timeline.php on line 20