MultiValueDictKeyError django, views.py error - django

Question

I'm getting MultiValueDictKeyError while using the POST method with Django.
this is my views.py submit function.
it seems like there is an error with the candidateId field and I don't understand why.
def submit_dept_member_application(request, application_id):
cv = request.FILES['cv']
letter = request.FILES['letter']
candidate_id = request.data['candidateId']
rank_id = request.data['requestedRankId']
application_state = {
'candidate_id': candidate_id,
'rank_id': rank_id,
'cv_filename': cv.name,
'letter_filename': letter.name,
}
creator = Profile.objects.get(user=request.user.id)
department = creator.department
applicant = Profile.objects.get(user=candidate_id)
rank = Rank.objects.get(id=rank_id)
try:
application = Application.objects.get(id=application_id)
# TODO - update application
except Application.DoesNotExist:
application = None
if application is None:
application = Application(creator=creator, applicant=applicant, desired_rank=rank,
application_state=application_state, department=department
)
application.save()
create_application_directory(application.id)
ApplicationStep.objects.update_or_create(
application=application, step_name=Step.STEP_1,
defaults={'can_update': True, 'can_cancel': True, 'currentStep': True}
)
copy_to_application_directory(cv, application.id)
copy_to_application_directory(letter, application.id)
addresee = 'devasap08#gmail.com' # TODO: change email to admin address
email_headline = 'New Application Created'
wanted_action = 'application_created'
sendEmail(addresee, email_headline, wanted_action, creator)
addresee = 'devasap08#gmail.com' # TODO: change email to creator address
email_headline = 'Application Successfully Created'
wanted_action = 'application_received'
sendEmail(addresee, email_headline, wanted_action, applicant)
return Response(application.id, status=status.HTTP_200_OK)
any suggestions on how to solve it?
Thank you!