diff --git a/src/pocketmine/network/mcpe/protocol/LoginPacket.php b/src/pocketmine/network/mcpe/protocol/LoginPacket.php
index 28a09b742..bad35b06b 100644
--- a/src/pocketmine/network/mcpe/protocol/LoginPacket.php
+++ b/src/pocketmine/network/mcpe/protocol/LoginPacket.php
@@ -163,6 +163,9 @@ class LoginPacket extends DataPacket{
 				$this->xuid = $claims["extraData"]["XUID"];
 			}
 		}
+		if(!$hasExtraData){
+			throw new \UnexpectedValueException("'extraData' not found in chain data");
+		}
 
 		$this->clientDataJwt = $buffer->get($buffer->getLInt());
 		$clientData = Utils::getJwtClaims($this->clientDataJwt);