Thanks, Eric!

I found this issue as well. The solution is explained here: https://github.com/tensorflow/models/issues/3252. Unfortunately, you’ll have to patch your local copy of TensorFlow.

Here is the relevant section of the link that explains what you need to do (quote below):

I had same error with Python3.5 and TF1.5. This causes tf_example.features.feature[self.field_name].bytes_list.value returns byte type instead of string type in metrics/tf_example_parser.StringParser.

So I changed tf_example_parser.StringParser below

class StringParser(data_parser.DataToNumpyParser):
  """Tensorflow Example string parser."""
  def __init__(self, field_name):
    self.field_name = field_name
  def parse(self, tf_example):
    if tf_example.features.feature[self.field_name].HasField("bytes_list"):
        result = tf_example.features.feature[self.field_name].bytes_list.value
        result = "".join([x if type(x)=='str' else x.decode('utf-8') for x in result])
    else:
        result = None
    return result