So, I am using an old version of InvMenu (because I am comfortable with it, and as you can see, I am a complete noob), and I want to get rid of the GUI by using removeWindow or removeAllWindows. If I try and use removeWindow: PHP: $inventory = $player->getInventory(); if($item->getId() == 345){ $player->removeWindow($inventory); sleep(1); $this->getTeleporter($player); return true; } This comes back: Code: 2020-03-12 [14:51:28] [Server thread/CRITICAL]: InvalidArgumentException: "Cannot remove fixed window 0 (pocketmine\inventory\PlayerInventory) from Epicthic" (EXCEPTION) in "src/pocketmine/Player" at line 3881 This is because I'm guessing it's a permanent window... If I try and use removeAllWindows: PHP: $inventory = $player->getInventory(); if($item->getId() == 345){ $player->removeAllWindows($inventory); sleep(1); $this->getTeleporter($player); return true; } Error (I don't understand it @-@): Code: 2020-03-12 [14:54:07] [Server thread/CRITICAL]: TypeError: "Argument 1 passed to pocketmine\Player::removeAllWindows() must be of the type bool, object given, called in C:\Users\schoo\OneDrive\Desktop\skyline_network\plugin_test_server\plugins\LobbyCore\src\ethaniccc\LobbyCore.php on line 2319" (EXCEPTION) in "src/pocketmine/Player" at line 3897 Can anyone help me? Please don't facepalm me, I know I'm a noob :d Thanks!