Fix

src/hdmf/common/resources.py

@@ -544,7 +544,7 @@ def add_ref_termset(self, **kwargs):
         if len(missing_terms)>0:
             return {"missing_terms": missing_terms}
 
-    def _validate_object(self, container, attribute, field):
+    def _validate_object(self, container, attribute, field, file):
         if attribute is None:  # Trivial Case
             relative_path = ''
             object_field = self._check_object_field(file=file,
@@ -588,6 +588,7 @@ def _validate_object(self, container, attribute, field):
                                                             container=parent,
                                                             relative_path=relative_path,
                                                             field=field)
+        return object_field
 
 
     @docval({'name': 'container', 'type': (str, AbstractContainer), 'default': None,
@@ -676,7 +677,7 @@ def add_ref(self, **kwargs):
                 msg = 'This entity already exists. Ignoring new entity uri'
                 warn(msg, stacklevel=3)
 
-        object_field = self._validate_object(container, attribute, field)
+        object_field = self._validate_object(container, attribute, field, file)
 
         #######################################
         # Validate Parameters and Populate HERD

src/hdmf/spec/spec.py

@@ -1056,7 +1056,7 @@ def is_inherited_spec(self, **kwargs):
                     self.__datasets[parent_name].get_attribute(spec_name) is not None):
                         return True
             else:
-                if (parent_name in self.__groups and self.is_inherited_group(parent_name) and :
+                if (parent_name in self.__groups and self.is_inherited_group(parent_name) and
                     self.__groups[parent_name].get_attribute(spec_name) is not None):
                         return True
         return False