1、错误原因

因为protobuf 模块是低版本的缺少buidler.py这个文件，可以通过pip3 install --upgrade protobuf 进行更新。这里注意最新版本的需要3.8 以上的Python 才能安装。如果是3.8以上安装不上可以用 " -i https://pypi.tuna.tsinghua.edu.cn/simple " 镜像源来解决。

2、Python版本过低解决方法

当Python的版本过低时，可以通过将buidler.py 文件复制到代码目录 直接引用来解决。当然如果上面的更新不可以的话也可以通过这种方法放到模块目录来解决。

（siste-packages/google/protobuf/internal/builder.py）

这里是buidler.py 文件代码

# Protocol Buffers - Google's data interchange format
# Copyright 2008 Google Inc.  All rights reserved.
#
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file or at
# https://developers.google.com/open-source/licenses/bsd

"""Builds descriptors, message classes and services for generated _pb2.py.

This file is only called in python generated _pb2.py files. It builds
descriptors, message classes and services that users can directly use
in generated code.
"""

__author__ = 'jieluo@google.com (Jie Luo)'

from google.protobuf.internal import enum_type_wrapper
from google.protobuf.internal import python_message
from google.protobuf import message as _message
from google.protobuf import reflection as _reflection
from google.protobuf import symbol_database as _symbol_database

_sym_db = _symbol_database.Default()


def BuildMessageAndEnumDescriptors(file_des, module):
  """Builds message and enum descriptors.

  Args:
    file_des: FileDescriptor of the .proto file
    module: Generated _pb2 module
  """

  def BuildNestedDescriptors(msg_des, prefix):
    for (name, nested_msg) in msg_des.nested_types_by_name.items():
      module_name = prefix + name.upper()
      module[module_name] = nested_msg
      BuildNestedDescriptors(nested_msg, module_name + '_')
    for enum_des in msg_des.enum_types:
      module[prefix + enum_des.name.upper()] = enum_des

  for (name, msg_des) in file_des.message_types_by_name.items():
    module_name = '_' + name.upper()
    module[module_name] = msg_des
    BuildNestedDescriptors(msg_des, module_name + '_')


def BuildTopDescriptorsAndMessages(file_des, module_name, module):
  """Builds top level descriptors and message classes.

  Args:
    file_des: FileDescriptor of the .proto file
    module_name: str, the name of generated _pb2 module
    module: Generated _pb2 module
  """

  def BuildMessage(msg_des):
    create_dict = {}
    for (name, nested_msg) in msg_des.nested_types_by_name.items():
      create_dict[name] = BuildMessage(nested_msg)
    create_dict['DESCRIPTOR'] = msg_des
    create_dict['__module__'] = module_name
    message_class = _reflection.GeneratedProtocolMessageType(
        msg_des.name, (_message.Message,), create_dict)
    _sym_db.RegisterMessage(message_class)
    return message_class

  # top level enums
  for (name, enum_des) in file_des.enum_types_by_name.items():
    module['_' + name.upper()] = enum_des
    module[name] = enum_type_wrapper.EnumTypeWrapper(enum_des)
    for enum_value in enum_des.values:
      module[enum_value.name] = enum_value.number

  # top level extensions
  for (name, extension_des) in file_des.extensions_by_name.items():
    module[name.upper() + '_FIELD_NUMBER'] = extension_des.number
    module[name] = extension_des

  # services
  for (name, service) in file_des.services_by_name.items():
    module['_' + name.upper()] = service

  # Build messages.
  for (name, msg_des) in file_des.message_types_by_name.items():
    module[name] = BuildMessage(msg_des)


def AddHelpersToExtensions(file_des):
  """no-op to keep old generated code work with new runtime.

  Args:
    file_des: FileDescriptor of the .proto file
  """
  # TODO: Remove this on-op
  return


def BuildServices(file_des, module_name, module):
  """Builds services classes and services stub class.

  Args:
    file_des: FileDescriptor of the .proto file
    module_name: str, the name of generated _pb2 module
    module: Generated _pb2 module
  """
  # pylint: disable=g-import-not-at-top
  from google.protobuf import service as _service
  from google.protobuf import service_reflection
  # pylint: enable=g-import-not-at-top
  for (name, service) in file_des.services_by_name.items():
    module[name] = service_reflection.GeneratedServiceType(
        name, (_service.Service,),
        dict(DESCRIPTOR=service, __module__=module_name))
    stub_name = name + '_Stub'
    module[stub_name] = service_reflection.GeneratedServiceStubType(
        stub_name, (module[name],),
        dict(DESCRIPTOR=service, __module__=module_name))