          fields = self.get_fields(serialize=False, data=data, nested=self.opts.nested)
  
          for field_name, field in fields.items():
              try:
                  clean_method = getattr(self, 'clean_%s' % field_name, None)
                  if clean_method:
                      source = field.source or field_name
                      data = clean_method(data, source)
              except ValidationError as err:
                  self._errors[field_name] = self._errors.get(field_name, []) + list(err.messages)
 
</s> remove         Run clean_<fieldname> validators on the serializer
 </s> add         Run validate_<fieldname> methods on the serializer </s> remove             def clean_content(self, attrs, source):
 </s> add             def validate_content(self, attrs, source):
                clean_method = getattr(self, 'validate_%s' % field_name, None)
          fields = self.get_fields(serialize=False, data=data, nested=self.opts.nested)
  
          for field_name, field in fields.items():
              try:
                clean_method = getattr(self, 'validate_%s' % field_name, None)
                  if clean_method:
                      source = field.source or field_name
                      data = clean_method(data, source)
              except ValidationError as err:
                  self._errors[field_name] = self._errors.get(field_name, []) + list(err.messages)
keep keep keep keep replace keep keep keep keep keep
 Switch from clean_<fieldname> to validate_<fieldname>, clarify documentation 
rest_framework/serializers.py