AttributeError: 'Node' object has no attribute 'output_masks'

Kindly guide me how to deal with this error:

Traceback (most recent call last):
File "train_bottleneck.py", line 224, in
_main()
File "train_bottleneck.py", line 30, in _main
freeze_body=2, weights_path='model_data/yolo_weights.h5') # make sure you know what you freeze
File "train_bottleneck.py", line 139, in create_model
model_body = yolo_body(image_input, num_anchors//3, num_classes)
File "D:\Yolov3CustomTraining\YOLOv3-object-detection-tutorial\YOLOv3-custom-training\yolo3\model.py", line 73, in yolo_body
darknet = Model(inputs, darknet_body(inputs))
File "D:\Yolov3CustomTraining\YOLOv3-object-detection-tutorial\YOLOv3-custom-training\yolo3\model.py", line 49, in darknet_body
x = DarknetConv2D_BN_Leaky(32, (3,3))(x)
File "D:\Yolov3CustomTraining\YOLOv3-object-detection-tutorial\YOLOv3-custom-training\yolo3\utils.py", line 17, in
return reduce(lambda f, g: lambda *a, **kw: g(f(*a, **kw)), funcs)
File "D:\Yolov3CustomTraining\YOLOv3-object-detection-tutorial\YOLOv3-custom-training\yolo3\utils.py", line 17, in
return reduce(lambda f, g: lambda *a, **kw: g(f(*a, **kw)), funcs)
File "C:\Users\PC\anaconda3\envs\myenv37\lib\site-packages\keras\engine\base_layer.py", line 443, in call
previous_mask = _collect_previous_mask(inputs)
File "C:\Users\PC\anaconda3\envs\myenv37\lib\site-packages\keras\engine\base_layer.py", line 1311, in _collect_previous_mask
mask = node.output_masks[tensor_index]
AttributeError: 'Node' object has no attribute 'output_masks'

@pythonlessons