Error in running the training

[Ar9av]

On running training command on parallel-crossencoder geting thne following

train_cmd(configs)

--> 197 Variable._execution_engine.run_backward(  # Calls into the C++ engine to run the backward pass
    198     tensors, grad_tensors_, retain_graph, create_graph, inputs,
    199     allow_unreachable=True, accumulate_grad=True)

RuntimeError: element 0 of tensors does not require grad and does not have a grad_fn