Error AttributeError: 'NoneType' object has no attribute '_inbound_nodes'

My model is as follows:
embed_dim = 16
vocab_size = vocab.num_words
np_text_tensor = np.array(text_tensor_train)
print(np_text_tensor.shape)
input_img = keras.Input(shape=(np.array(text_tensor).shape[1], np.array(text_tensor).shape[2]))
print(input_img.shape)
list_input = []
for i in range(np_text_tensor.shape[1]):
ExpandInputs = layers.Lambda(lambda x: tf.expand_dims(x,axis=1))
x = layers.Embedding(input_dim=vocab_size, output_dim=embed_dim, mask_zero=True)(ExpandInputs(input_img[:,i,:]))
Transpose1 = layers.Lambda(lambda x: tf.transpose(x, perm = [0,1,3,2]))
x = Transpose1(x)
x = layers.Conv2D(16, (1,1), activation=‘relu’, padding=‘same’, name=“name4”+str(i))(x)
x = layers.AveragePooling2D((1,1), padding=‘same’)(x)
x = layers.Conv2D(8, (1,1), activation=‘relu’, padding=‘same’, name=“name5”+str(i))(x)
encoded = x = layers.UpSampling2D((1,1))(x)
x = layers.Conv2D(16, (1,1), activation=‘relu’, padding=‘same’, name=“name6”+str(i))(encoded)
x = layers.UpSampling2D((1,1))(x)
x = layers.Conv2D(np.array(text_tensor).shape[2], (1,1), padding=‘same’, name=“name10”+str(i))(x)
x = layers.Flatten()(x)
ExpandDims =layers.Lambda(lambda x: tf.expand_dims(layers.Dense(np.array(text_tensor).shape[2])(x), 1) )
decoded = layers.Permute((2,1))(ExpandDims(x))
list_input.append(decoded)
print(layers.Concatenate()(list_input).shape)
Transpose = layers.Lambda(lambda x: tf.transpose(x, perm=[0,2,1]), name=“Transpose1”)
autoencoder = keras.Model(input_img, Transpose(layers.Concatenate()(list_input)))
optimiser = Adam(lr=0.01, beta_1=0.9, beta_2=0.999, amsgrad=False, decay=1e-8)
autoencoder.compile(optimizer=optimiser, loss=‘mean_squared_error’)
autoencoder.summary()

But I am getting the following error…any help appreciated
(None, 16, 15)

AttributeError Traceback (most recent call last)
/var/folders/4y/trqfxs_d5x7clsdrtcpdlrrh0000gn/T/ipykernel_6243/1380911180.py in
1 print(layers.Concatenate()(list_input).shape)
2 Transpose = layers.Lambda(lambda x: K.transpose(x), name=“Transpose1”)
----> 3 autoencoder = keras.Model(input_img, Transpose(layers.Concatenate()(list_input)))
4 optimiser = Adam(lr=0.01, beta_1=0.9, beta_2=0.999, amsgrad=False, decay=1e-8)
5 autoencoder.compile(optimizer=optimiser, loss=‘mean_squared_error’)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/legacy/interfaces.py in wrapper(*args, **kwargs)
89 warnings.warn('Update your ' + object_name + ' call to the ’ +
90 'Keras 2 API: ’ + signature, stacklevel=2)
—> 91 return func(*args, **kwargs)
92 wrapper._original_function = func
93 return wrapper

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in init(self, *args, **kwargs)
92 ‘inputs’ in kwargs and ‘outputs’ in kwargs):
93 # Graph network
—> 94 self._init_graph_network(*args, **kwargs)
95 else:
96 # Subclassed network

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in _init_graph_network(self, inputs, outputs, name, **kwargs)
239 # Keep track of the network’s nodes and layers.
240 nodes, nodes_by_depth, layers, layers_by_depth = _map_graph_network(
→ 241 self.inputs, self.outputs)
242 self._network_nodes = nodes
243 self._nodes_by_depth = nodes_by_depth

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in _map_graph_network(inputs, outputs)
1432 layer=layer,
1433 node_index=node_index,
→ 1434 tensor_index=tensor_index)
1435
1436 for node in reversed(nodes_in_decreasing_depth):

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1419 tensor_index = node.tensor_indices[i]
1420 build_map(x, finished_nodes, nodes_in_progress, layer,
→ 1421 node_index, tensor_index)
1422
1423 finished_nodes.add(node)

/opt/anaconda3/envs/tflatest4/lib/python3.7/site-packages/keras/engine/network.py in build_map(tensor, finished_nodes, nodes_in_progress, layer, node_index, tensor_index)
1391 ValueError: if a cycle is detected.
1392 “”"
→ 1393 node = layer._inbound_nodes[node_index]
1394
1395 # Prevent cycles.

AttributeError: ‘NoneType’ object has no attribute ‘_inbound_nodes’

Hi @Raman_S

Welcome to the TensorFlow Forum!

Could you please let us know if this issue still persists? If so, Please share the standalone code along with the details of system OS, installed TensorFlow and Python version in your system. Thank you.