iterator should return strings, not bytes (did you open the file in text mode?) while uploading csv in django

I want to upload csv file and store in database. when I click the submit button I get the following error

Environment:


Request Method: POST
Request URL: http://localhost:8000/csv

Django Version: 1.9
Python Version: 3.4.3
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.gis',
 'django.contrib.admindocs',
 'world',
 'pft',
 'wms',
 'djgeojson',
 'html5',
 'geoexplorer']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']



Traceback:

File "C:\Python34\lib\site-packages\django\core\handlers\base.py" in get_response
  149.                     response = self.process_exception_by_middleware(e, request)

File "C:\Python34\lib\site-packages\django\core\handlers\base.py" in get_response
  147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "C:\Python34\lib\site-packages\django\contrib\auth\decorators.py" in _wrapped_view
  23.                 return view_func(request, *args, **kwargs)

File "C:\Python34\Lib\site-packages\django\bin\geodjango\pft\views.py" in add_multiple_accounts
  95.              csv_result, rows_error = utils.handle_uploaded_file(file, utils.account_valid_fields, utils.create_account_in_db)

File "C:\Python34\Lib\site-packages\django\bin\geodjango\pft\utils.py" in handle_uploaded_file
  24.     if not valid_fields_method(data.fieldnames):

File "C:\Python34\lib\csv.py" in fieldnames
  96.                 self._fieldnames = next(self.reader)

Exception Type: Error at /csv
Exception Value: iterator should return strings, not bytes (did you open the file in text mode?)

my handle file upload function is below-utils.py

def handle_uploaded_file(file, valid_fields_method, record_creation_function):
    file.seek(0)
    sniffdialect = csv.reader(codecs.iterdecode(file, 'utf-8')
    file.seek(0)
    data = csv.DictReader(file, dialect=sniffdialect)

    if not valid_fields_method(data.fieldnames):
        return False, -1

    result, rows_error = record_creation_function(data)

    return result, rows_error

I'm using django 1.9 and python 3.4. Please help ! I'm struggling for past 2 days.