Facing this error

Traceback (most recent call last):
File "encode_images.py", line 80, in
main()
File "encode_images.py", line 53, in main
generator = Generator(Gs_network, args.batch_size, randomize_noise=args.randomize_noise)
File "/content/gdrive/My Drive/RI/stylegan-encoder/encoder/generator_model.py", line 35, in init
self.generator_output = self.graph.get_tensor_by_name('G_synthesis_1/_Run/concat:0')
File "/usr/local/lib/python3.6/dist-packages/tensorflow_core/python/framework/ops.py", line 3783, in get_tensor_by_name
return self.as_graph_element(name, allow_tensor=True, allow_operation=False)
File "/usr/local/lib/python3.6/dist-packages/tensorflow_core/python/framework/ops.py", line 3607, in as_graph_element
return self._as_graph_element_locked(obj, allow_tensor, allow_operation)
File "/usr/local/lib/python3.6/dist-packages/tensorflow_core/python/framework/ops.py", line 3649, in _as_graph_element_locked
"graph." % (repr(name), repr(op_name)))
KeyError: "The name 'G_synthesis_1/_Run/concat:0' refers to a Tensor which does not exist. The operation, 'G_synthesis_1/_Run/concat', does not exist in the graph."