          """
          field_timezone = getattr(self, 'timezone', self.default_timezone())
  
          if (field_timezone is not None) and not timezone.is_aware(value):
              return timezone.make_aware(value, field_timezone)
          elif (field_timezone is None) and timezone.is_aware(value):
              return timezone.make_naive(value, utc)
          return value
  
      def default_timezone(self):
 
</s> remove         '2017-03-12T02:30:00': [
            'Datetime can not be converted to server timezone due to NonExistentTimeError.'],
        '2017-11-05T01:30:00': [
            'Datetime can not be converted to server timezone due to AmbiguousTimeError.']
 </s> add         '2017-03-12T02:30:00': ['Datetime can not be represented in timezone "America/New_York".'],
        '2017-11-05T01:30:00': ['Datetime can not be represented in timezone "America/New_York".'] </s> remove from django.utils.timezone import utc, pytz
 </s> add from django.utils.timezone import pytz, utc
            try:
                return timezone.make_aware(value, field_timezone)
            except Exception:
                self.fail('make_aware', timezone=field_timezone)
          """
          field_timezone = getattr(self, 'timezone', self.default_timezone())
  
          if (field_timezone is not None) and not timezone.is_aware(value):
            try:
                return timezone.make_aware(value, field_timezone)
            except Exception:
                self.fail('make_aware', timezone=field_timezone)
          elif (field_timezone is None) and timezone.is_aware(value):
              return timezone.make_naive(value, utc)
          return value
  
      def default_timezone(self):
keep keep keep keep replace keep keep keep keep keep
 Fix bug for not existent or ambiguous datetime during native to aware conversion in timezone with DST.
Ref: #4986 
rest_framework/fields.py