bert-serving-server 启动出错fail to optimize the graph!TypeError: 'NoneType' object is not iterable

问题遇到的现象和发生背景
问题相关代码,请勿粘贴截图
运行结果及报错内容
我的解答思路和尝试过的方法
我想要达到的结果
C:\Users\Administrator>bert-serving-start -model_dir E:\chinese_L-12_H-768_A-12\ -num_worker=2
usage: E:\Python3.6.8\Scripts\bert-serving-start -model_dir E:\chinese_L-12_H-768_A-12\ -num_worker=2
                 ARG   VALUE
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           ckpt_name = bert_model.ckpt
         config_name = bert_config.json
                cors = *
                 cpu = False
          device_map = []
       do_lower_case = True
  fixed_embed_length = False
                fp16 = False
 gpu_memory_fraction = 0.5
       graph_tmp_dir = None
    http_max_connect = 10
           http_port = None
        mask_cls_sep = False
      max_batch_size = 256
         max_seq_len = 25
           model_dir = E:\chinese_L-12_H-768_A-12\
          num_worker = 2
       pooling_layer = [-2]
    pooling_strategy = REDUCE_MEAN
                port = 5555
            port_out = 5556
       prefetch_size = 10
 priority_batch_size = 16
show_tokens_to_client = False
     tuned_model_dir = None
             verbose = False
                 xla = False

I:[35mVENTILATOR[0m:freeze, optimize and export graph, could take a while...
I:[36mGRAPHOPT[0m:model config: E:\chinese_L-12_H-768_A-12\bert_config.json
I:[36mGRAPHOPT[0m:checkpoint: E:\chinese_L-12_H-768_A-12\bert_model.ckpt
I:[36mGRAPHOPT[0m:build graph...
I:[36mGRAPHOPT[0m:load parameters from checkpoint...
I:[36mGRAPHOPT[0m:optimize...
I:[36mGRAPHOPT[0m:freeze...
I:[36mGRAPHOPT[0m:write graph to a tmp file: C:\Users\ADMINI~1\AppData\Local\Temp\tmpoubpvmkr
E:[36mGRAPHOPT[0m:fail to optimize the graph!
Traceback (most recent call last):
  File "E:\Python3.6.8\lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "E:\Python3.6.8\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "E:\Python3.6.8\Scripts\bert-serving-start.exe\__main__.py", line 7, in <module>
  File "E:\Python3.6.8\lib\site-packages\bert_serving\server\cli\__init__.py", line 4, in main
    with BertServer(get_run_args()) as server:
  File "E:\Python3.6.8\lib\site-packages\bert_serving\server\__init__.py", line 70, in __init__
    self.graph_path, self.bert_config = pool.apply(optimize_graph, (self.args,))
TypeError: 'NoneType' object is not iterable

windows环境 请问这种问题怎么解决呢 试了很多方法 我的tensorflow版本是1.11.0有的说换成1.10.0我换过,更不行。我的python是3.6