Google Play游戏实时多人游戏：NETWORK_ERROR_OPERATION_FAILED

Question

我正在尝试将Real-Time Multiplayer应用到我的Android应用中。但它崩溃了以下错误：

java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.Object com.google.android.gms.games.multiplayer.realtime.Room.freeze()' on a null object reference`

Google Play给出了以下错误：错误代码6，NETWORK_ERROR_OPERATION_FAILED

中对Android文档中此错误的描述没有帮助

尝试执行需要网络访问的操作时发生网络错误。

这些是我的代码的一些部分：

 private RoomConfig.Builder makeBasicRoomConfigBuilder() {
    return RoomConfig.builder(updateListener)
            .setMessageReceivedListener(realTimeMessageReceivedListener)
            .setRoomStatusUpdateListener(roomStatusUpdateListener);
}

private void startQuickGame() {
    // auto-match criteria to invite one random automatch opponent.
    // You can also specify more opponents (up to 3).
    Bundle am = RoomConfig.createAutoMatchCriteria(1, 1, 0);

    // build the room config:
    RoomConfig.Builder roomConfigBuilder = makeBasicRoomConfigBuilder();
    roomConfigBuilder.setAutoMatchCriteria(am);
    RoomConfig roomConfig = roomConfigBuilder.build();

    // create room:
    Games.RealTimeMultiplayer.create(mGoogleApiClient, roomConfig);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
    // TODO:go to game screen
}

导致此次崩溃的原因是什么？如何解决？

编辑：创建房间时，错误发生在开头。无论是快速游戏还是挑选对手都无关紧要