There are some threads on the internet telling you to do this as a fix: function check_some_other_plugin() { if ( is_plugin_active(‘some-plugin.php’) ) { … } } add_action( ‘admin_init’, ‘check_some_other_plugin’ ); That solution didn’t do anything for me, all I had to do was include plugin.php on my file like this: include_once(‘wp-admin/includes/plugin.php’); And the error was […]