Solution:1
is_user_logged_in()
is located in wp-includes/pluggable.php. So please include this file in your plugin file and check.
Solution:1
is_user_logged_in()
is located in wp-includes/pluggable.php. So please include this file in your plugin file and check.
Solution:2
Try with
$user = wp_get_current_user();
if($user->ID != 0 or $user->ID != null) ...