this should fix the issue with the failing tests

Author: Andrei Neagu

packages/models-library/src/models_library/api_schemas_webserver/groups.py

@@ -100,11 +100,6 @@ class GroupCreate(InputSchema):
     description: str
     thumbnail: AnyUrl | None = None
 
-    @field_validator("thumbnail")
-    @classmethod
-    def _transform_to_string_for_db(cls, v: AnyUrl | None) -> str | None:
-        return f"{v}" if v is not None else v
-
 
 class GroupUpdate(InputSchema):
     label: str | None = None

services/web/server/src/simcore_service_webserver/groups/_handlers.py

@@ -150,7 +150,7 @@ async def create_group(request: web.Request):
     """Creates organization groups"""
     req_ctx = _GroupsRequestContext.model_validate(request)
     create = await parse_request_body_as(GroupCreate, request)
-    new_group = create.model_dump(exclude_unset=True)
+    new_group = create.model_dump(mode="json", exclude_unset=True)
 
     created_group = await api.create_user_group(request.app, req_ctx.user_id, new_group)
     assert GroupGet.model_validate(created_group) is not None  # nosec