Traceback (most recent call last):


 "<stdin>", line 1, in <module>
TypeError: serialize() missing 1 required positional argument: 'value'

Traceback (most recent call last):


 "/content/detectron2/detectron2/engine/train_loop.py", line 134, in train

self.run_step()


 "/content/detectron2/detectron2/engine/defaults.py", line 429, in run_step

self._trainer.run_step()


 "/content/detectron2/detectron2/engine/train_loop.py", line 236, in run_step

losses.backward()


 "/usr/local/lib/python3.6/dist-packages/torch/tensor.py", line 221, in backward

torch.autograd.backward(self, gradient, retain_graph, create_graph)


 "/usr/local/lib/python3.6/dist-packages/torch/autograd/__init__.py", line 132, in backward

allow_unreachable=True)
# allow_unreachable flag
RuntimeError: element 0 of tensors does not require grad and does not have a grad_fn
