运行到这行代码时optimizer.minimize(self.g_loss_A, parameter_list=vars)出错，

错误信息：

Traceback (most recent call last):
File "E:\pycharm\PyCharm Community Edition 2019.1.3\helpers\pydev\pydevd.py", line 1758, in
main()
File "E:\pycharm\PyCharm Community Edition 2019.1.3\helpers\pydev\pydevd.py", line 1752, in main
globals = debugger.run(setup['file'], None, None, is_module)
File "E:\pycharm\PyCharm Community Edition 2019.1.3\helpers\pydev\pydevd.py", line 1147, in run
pydev_imports.execfile(file, globals, locals) # execute the script
File "E:\pycharm\PyCharm Community Edition 2019.1.3\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
exec(compile(contents+"\n", file, 'exec'), glob, loc)
File "E:/MainFiles/DeepLearning/paddle cycleGAN/train.py", line 315, in
train(args)
File "E:/MainFiles/DeepLearning/paddle cycleGAN/train.py", line 93, in train
g_A_trainer = GATrainer(input_A, input_B)
File "E:\MainFiles\DeepLearning\paddle cycleGAN\trainer.py", line 73, in __init__
optimizer.minimize(self.g_loss_A, parameter_list=vars)
File "", line 2, in minimize
File "D:\Anaconda3\lib\site-packages\paddle\fluid\wrapped_decorator.py", line 25, in __impl__
return wrapped_func(*args, **kwargs)
File "D:\Anaconda3\lib\site-packages\paddle\fluid\dygraph\base.py", line 87, in __impl__
return func(*args, **kwargs)
File "D:\Anaconda3\lib\site-packages\paddle\fluid\optimizer.py", line 609, in minimize
no_grad_set=no_grad_set)
File "D:\Anaconda3\lib\site-packages\paddle\fluid\optimizer.py", line 494, in backward
no_grad_set, callbacks)
File "D:\Anaconda3\lib\site-packages\paddle\fluid\backward.py", line 706, in append_backward
_append_backward_vars_(root_block, fwd_op_num, grad_to_var, grad_info_map)
File "D:\Anaconda3\lib\site-packages\paddle\fluid\backward.py", line 518, in _append_backward_vars_
op_desc.infer_shape(block.desc)
IndexError: invalid unordered_map key

这个错误会由什么引起？怎么改。。