Fatal error: Uncaught Error: Call to undefined function add_action() in C:\xampp\htdocs\wp-content\plugins\3d-viewer\inc\admin.php:8 Stack trace: #0 C:\xampp\htdocs\wp-content\plugins\3d-viewer\inc\admin.php(115): BP3DAdmin->__construct() #1 {main} thrown in C:\xampp\htdocs\wp-content\plugins\3d-viewer\inc\admin.php on line 8