Train on Google Colab not working

[PhilippTriet]

I always get the following error message when I try to train it on Google Colab. It works local and on Azure.

RuntimeError Traceback (most recent call last)

in ()
24 config['model']['class_scale'],
25 config['model']['object_scale'],
---> 26 config['model']['no_object_scale'])
27
28 # 2. Load the pretrained weights (if any)

5 frames

/content/drive/My Drive/Colab Notebooks/yolo/frontend.py in create_yolo(architecture, labels, input_size, anchors, coord_scale, class_scale, object_scale, no_object_scale)
33 n_classes = len(labels)
34 n_boxes = int(len(anchors)/2)
---> 35 yolo_network = create_yolo_network(architecture, input_size, n_classes, n_boxes)
36 yolo_loss = YoloLoss(yolo_network.get_grid_size(),
37 n_classes,

/content/drive/My Drive/Colab Notebooks/yolo/backend/network.py in create_yolo_network(architecture, input_size, nb_classes, nb_box)
17 input_size,
18 nb_classes,
---> 19 nb_box)
20 return yolo_net
21

/content/drive/My Drive/Colab Notebooks/yolo/backend/network.py in init(self, feature_extractor, input_size, nb_classes, nb_box)
38 grid_size = 7
39
---> 40 grid_size = feature_extractor.get_output_size()
41
42 print(grid_size)

/content/drive/My Drive/Colab Notebooks/yolo/backend/utils/feature.py in get_output_size(self)
59
60 def get_output_size(self):
---> 61 output_shape = self.feature_extractor.get_output_shape_at(-1)
62 assert output_shape[1] == output_shape[2]
63 return output_shape[1]

/usr/local/lib/python3.6/dist-packages/tensorflow/python/keras/engine/base_layer.py in get_output_shape_at(self, node_index)
2028 """
2029 return self._get_node_attribute_at_index(node_index, 'output_shapes',
-> 2030 'output shape')
2031
2032 @doc_controls.do_not_doc_inheritable

/usr/local/lib/python3.6/dist-packages/tensorflow/python/keras/engine/base_layer.py in _get_node_attribute_at_index(self, node_index, attr, attr_name)
2601 if not self._inbound_nodes:
2602 raise RuntimeError('The layer has never been called '
-> 2603 'and thus has no defined ' + attr_name + '.')
2604 if not len(self._inbound_nodes) > node_index:
2605 raise ValueError('Asked to get ' + attr_name + ' at node ' +

RuntimeError: The layer has never been called and thus has no defined output shape.