May 10 05:59:52 openedx2020-ap01 [service_variant=lms][celery.app.trace][env:sandbox] ERROR [openedx2020-ap01  1427408] [user None] [ip None] [trace.py:255] - Task lms.djangoapps.instructor_task.tasks.calculate_grades_csv[76479a4b-8ec5-462a-b01f-ed0ceec6699a] raised unexpected: AttributeError('Field display_name does not exist')
Traceback (most recent call last):
  File "/edx/app/edxapp/edx-platform/openedx/core/djangoapps/content/block_structure/block_structure.py", line 304, in __getattr__
    return self.fields[field_name]
KeyError: 'display_name'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/edx/app/edxapp/venvs/edxapp/lib/python3.8/site-packages/celery/app/trace.py", line 412, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/edx/app/edxapp/venvs/edxapp/lib/python3.8/site-packages/celery/app/trace.py", line 704, in __protected_call__
    return self.run(*args, **kwargs)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks.py", line 191, in calculate_grades_csv
    return run_main_task(entry_id, task_fn, action_name)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/runner.py", line 120, in run_main_task
    task_progress = task_fcn(entry_id, course_id, task_input, action_name)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/grades.py", line 418, in generate
    return CourseGradeReport()._generate(context)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/grades.py", line 430, in _generate
    success_rows, error_rows = self._compile(context, batched_rows)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/grades.py", line 472, in _compile
    success_rows, error_rows = zip(*batched_rows)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/grades.py", line 464, in _batched_rows
    yield self._rows_for_users(context, users)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/grades.py", line 698, in _rows_for_users
    self._user_grades(course_grade, context) +
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/grades.py", line 578, in _user_grades
    subsection_grades, subsection_grades_results = self._user_subsection_grades(
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/instructor_task/tasks_helper/grades.py", line 598, in _user_subsection_grades
    subsection_grade = course_grade.subsection_grade(subsection_location)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/grades/course_grade.py", line 64, in subsection_grade
    return self._get_subsection_grade(self.course_data.effective_structure[subsection_key])
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/grades/course_grade.py", line 292, in _get_subsection_grade
    return self._subsection_grade_factory.create(subsection, read_only=True)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/grades/subsection_grade_factory.py", line 53, in create
    subsection_grade = CreateSubsectionGrade(
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/grades/subsection_grade.py", line 300, in __init__
    super(CreateSubsectionGrade, self).__init__(subsection, all_total, graded_total)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/grades/subsection_grade.py", line 149, in __init__
    super(NonZeroSubsectionGrade, self).__init__(subsection)
  File "/edx/app/edxapp/edx-platform/lms/djangoapps/grades/subsection_grade.py", line 29, in __init__
    self.display_name = escape(block_metadata_utils.display_name_with_default(subsection))
  File "/edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/block_metadata_utils.py", line 44, in display_name_with_default
    block.display_name if block.display_name is not None
  File "/edx/app/edxapp/edx-platform/openedx/core/djangoapps/content/block_structure/block_structure.py", line 306, in __getattr__
    raise AttributeError(u"Field {0} does not exist".format(field_name))