diff --git a/inventory_management_system_api/routers/v1/catalogue_category.py b/inventory_management_system_api/routers/v1/catalogue_category.py
index 8031311d..a42ab867 100644
--- a/inventory_management_system_api/routers/v1/catalogue_category.py
+++ b/inventory_management_system_api/routers/v1/catalogue_category.py
@@ -186,8 +186,9 @@ def partial_update_catalogue_category(
         logger.exception(message)
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=message) from exc
     except ChildElementsExistError as exc:
-        message = ("Catalogue category has child elements, so the following fields cannot be updated: "
-            + ', '.join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS))
+        message = "Catalogue category has child elements, so the following fields cannot be updated: " + ", ".join(
+            CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS
+        )
         logger.exception(message)
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail=message) from exc
     except DuplicateRecordError as exc:
diff --git a/inventory_management_system_api/routers/v1/catalogue_item.py b/inventory_management_system_api/routers/v1/catalogue_item.py
index 7605fcc2..31d0f752 100644
--- a/inventory_management_system_api/routers/v1/catalogue_item.py
+++ b/inventory_management_system_api/routers/v1/catalogue_item.py
@@ -162,8 +162,9 @@ def partial_update_catalogue_item(
         logger.exception(message)
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail=message) from exc
     except ChildElementsExistError as exc:
-        message = ("Catalogue item has child elements, so the following fields cannot be updated: "
-            + ', '.join(CATALOGUE_ITEM_WITH_CHILD_NON_EDITABLE_FIELDS))
+        message = "Catalogue item has child elements, so the following fields cannot be updated: " + ", ".join(
+            CATALOGUE_ITEM_WITH_CHILD_NON_EDITABLE_FIELDS
+        )
         logger.exception(message)
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail=message) from exc
     except InvalidActionError as exc:
diff --git a/test/e2e/test_catalogue_category.py b/test/e2e/test_catalogue_category.py
index 55b397c5..a57177cd 100644
--- a/test/e2e/test_catalogue_category.py
+++ b/test/e2e/test_catalogue_category.py
@@ -993,7 +993,7 @@ def test_partial_update_non_leaf_to_leaf_when_has_child_catalogue_category(self)
         self.check_patch_catalogue_category_failed_with_detail(
             409,
             "Catalogue category has child elements, so the following fields cannot be updated: "
-                + ', '.join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS)
+            + ", ".join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS),
         )
 
     def test_partial_update_leaf_all_valid_values_when_no_children(self):
@@ -1040,7 +1040,7 @@ def test_partial_update_leaf_to_non_leaf_when_has_child_catalogue_item(self):
         self.check_patch_catalogue_category_failed_with_detail(
             409,
             "Catalogue category has child elements, so the following fields cannot be updated: "
-                + ', '.join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS)
+            + ", ".join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS),
         )
 
     def test_partial_update_leaf_properties_when_has_child_catalogue_item(self):
@@ -1054,7 +1054,7 @@ def test_partial_update_leaf_properties_when_has_child_catalogue_item(self):
         self.check_patch_catalogue_category_failed_with_detail(
             409,
             "Catalogue category has child elements, so the following fields cannot be updated: "
-                + ', '.join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS)
+            + ", ".join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS),
         )
 
     def test_partial_update_leaf_to_non_leaf_with_properties(self):
@@ -1099,7 +1099,7 @@ def test_partial_update_is_leaf_with_child_catalogue_category(self):
         self.check_patch_catalogue_category_failed_with_detail(
             409,
             "Catalogue category has child elements, so the following fields cannot be updated: "
-                + ', '.join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS)
+            + ", ".join(CATALOGUE_CATEGORY_WITH_CHILD_NON_EDITABLE_FIELDS),
         )
 
     def test_partial_update_leaf_properties(self):
diff --git a/test/e2e/test_catalogue_item.py b/test/e2e/test_catalogue_item.py
index 4246ef1b..1816d945 100644
--- a/test/e2e/test_catalogue_item.py
+++ b/test/e2e/test_catalogue_item.py
@@ -1188,7 +1188,7 @@ def test_partial_update_manufacturer_id_with_children(self):
         self.check_patch_catalogue_item_failed_with_detail(
             409,
             "Catalogue item has child elements, so the following fields cannot be updated: "
-                + ', '.join(CATALOGUE_ITEM_WITH_CHILD_NON_EDITABLE_FIELDS)
+            + ", ".join(CATALOGUE_ITEM_WITH_CHILD_NON_EDITABLE_FIELDS),
         )
 
     def test_partial_update_manufacturer_id_with_non_existent_id(self):
@@ -1465,7 +1465,7 @@ def test_partial_update_properties_with_children(self):
         self.check_patch_catalogue_item_failed_with_detail(
             409,
             "Catalogue item has child elements, so the following fields cannot be updated: "
-                + ', '.join(CATALOGUE_ITEM_WITH_CHILD_NON_EDITABLE_FIELDS)
+            + ", ".join(CATALOGUE_ITEM_WITH_CHILD_NON_EDITABLE_FIELDS),
         )
 
     def test_partial_update_obsolete_replacement_catalogue_item_id(self):