diff --git a/packages/models-library/src/models_library/rest_ordering.py b/packages/models-library/src/models_library/rest_ordering.py
index b042950c352..eb2a5adf5f4 100644
--- a/packages/models-library/src/models_library/rest_ordering.py
+++ b/packages/models-library/src/models_library/rest_ordering.py
@@ -27,10 +27,10 @@ class OrderBy(BaseModel):
 
 
 class _BaseOrderQueryParams(RequestParameters):
-    order_by: OrderBy | None = None
+    order_by: OrderBy
 
 
-def create_ordering_query_model_classes(
+def create_ordering_query_model_class(
     *,
     ordering_fields: set[str],
     default: OrderBy,
diff --git a/packages/models-library/tests/test_rest_ordering.py b/packages/models-library/tests/test_rest_ordering.py
index 6db89d4bb48..b2e6e0765b5 100644
--- a/packages/models-library/tests/test_rest_ordering.py
+++ b/packages/models-library/tests/test_rest_ordering.py
@@ -1,16 +1,19 @@
+import pickle
+
 import pytest
 from common_library.json_serialization import json_dumps
 from models_library.basic_types import IDStr
 from models_library.rest_ordering import (
     OrderBy,
     OrderDirection,
-    create_ordering_query_model_classes,
+    create_ordering_query_model_class,
 )
 from pydantic import (
     BaseModel,
     ConfigDict,
     Field,
     Json,
+    TypeAdapter,
     ValidationError,
     field_validator,
 )
@@ -47,8 +50,72 @@ def _validate_order_by_field(cls, v):
     )
 
 
+@pytest.mark.xfail(
+    reason="create_ordering_query_model_class.<locals>._OrderBy is still not pickable"
+)
+def test_pickle_ordering_query_model_class():
+    OrderQueryParamsModel = create_ordering_query_model_class(
+        ordering_fields={"name", "description"},
+        default=OrderBy(field=IDStr("name"), direction=OrderDirection.DESC),
+    )
+
+    data = {"order_by": {"field": "name", "direction": "asc"}}
+    query_model = OrderQueryParamsModel.model_validate(data)
+
+    # https://docs.pydantic.dev/latest/concepts/serialization/#pickledumpsmodel
+    expected = query_model.order_by
+
+    # see https://github.com/ITISFoundation/osparc-simcore/pull/6828
+    # FAILURE: raises `AttributeError: Can't pickle local object 'create_ordering_query_model_class.<locals>._OrderBy'`
+    data = pickle.dumps(expected)
+
+    loaded = pickle.loads(data)
+    assert loaded == expected
+
+
+def test_conversion_order_by_from_query_to_domain_model():
+    OrderQueryParamsModel = create_ordering_query_model_class(
+        ordering_fields={"modified_at", "name", "description"},
+        default=OrderBy(field=IDStr("modified_at"), direction=OrderDirection.DESC),
+    )
+
+    # normal
+    data = {"order_by": {"field": "modified_at", "direction": "asc"}}
+    query_model = OrderQueryParamsModel.model_validate(data)
+
+    expected_data = data["order_by"]
+
+    assert type(query_model.order_by) is not OrderBy
+    assert isinstance(query_model.order_by, OrderBy)
+
+    # NOTE: This does NOT convert to OrderBy but has correct data
+    order_by = TypeAdapter(OrderBy).validate_python(
+        query_model.order_by, from_attributes=True
+    )
+    assert type(order_by) is not OrderBy
+    assert order_by.model_dump(mode="json") == expected_data
+
+    order_by = OrderBy.model_validate(query_model.order_by.model_dump())
+    assert type(order_by) is OrderBy
+    assert order_by.model_dump(mode="json") == expected_data
+
+    # NOTE: This does NOT convert to OrderBy but has correct data
+    order_by = OrderBy.model_validate(query_model.order_by, from_attributes=True)
+    assert type(order_by) is not OrderBy
+    assert order_by.model_dump(mode="json") == expected_data
+
+    order_by = OrderBy(**query_model.order_by.model_dump())
+    assert type(order_by) is OrderBy
+    assert order_by.model_dump(mode="json") == expected_data
+
+    # we should use this !!!
+    order_by = OrderBy.model_construct(**query_model.order_by.model_dump())
+    assert type(order_by) is OrderBy
+    assert order_by.model_dump(mode="json") == expected_data
+
+
 def test_ordering_query_model_class_factory():
-    BaseOrderingQueryModel = create_ordering_query_model_classes(
+    BaseOrderingQueryModel = create_ordering_query_model_class(
         ordering_fields={"modified_at", "name", "description"},
         default=OrderBy(field=IDStr("modified_at"), direction=OrderDirection.DESC),
         ordering_fields_api_to_column_map={"modified_at": "modified_column"},
@@ -77,7 +144,7 @@ class OrderQueryParamsModel(BaseOrderingQueryModel):
 
 def test_ordering_query_model_class__fails_with_invalid_fields():
 
-    OrderQueryParamsModel = create_ordering_query_model_classes(
+    OrderQueryParamsModel = create_ordering_query_model_class(
         ordering_fields={"modified", "name", "description"},
         default=OrderBy(field=IDStr("modified"), direction=OrderDirection.DESC),
     )
@@ -94,7 +161,7 @@ def test_ordering_query_model_class__fails_with_invalid_fields():
 
 
 def test_ordering_query_model_class__fails_with_invalid_direction():
-    OrderQueryParamsModel = create_ordering_query_model_classes(
+    OrderQueryParamsModel = create_ordering_query_model_class(
         ordering_fields={"modified", "name", "description"},
         default=OrderBy(field=IDStr("modified"), direction=OrderDirection.DESC),
     )
@@ -112,7 +179,7 @@ def test_ordering_query_model_class__fails_with_invalid_direction():
 
 def test_ordering_query_model_class__defaults():
 
-    OrderQueryParamsModel = create_ordering_query_model_classes(
+    OrderQueryParamsModel = create_ordering_query_model_class(
         ordering_fields={"modified", "name", "description"},
         default=OrderBy(field=IDStr("modified"), direction=OrderDirection.DESC),
         ordering_fields_api_to_column_map={"modified": "modified_at"},
@@ -142,7 +209,7 @@ def test_ordering_query_model_class__defaults():
 
 
 def test_ordering_query_model_with_map():
-    OrderQueryParamsModel = create_ordering_query_model_classes(
+    OrderQueryParamsModel = create_ordering_query_model_class(
         ordering_fields={"modified", "name", "description"},
         default=OrderBy(field=IDStr("modified"), direction=OrderDirection.DESC),
         ordering_fields_api_to_column_map={"modified": "some_db_column_name"},
@@ -155,7 +222,7 @@ def test_ordering_query_model_with_map():
 
 def test_ordering_query_parse_json_pre_validator():
 
-    OrderQueryParamsModel = create_ordering_query_model_classes(
+    OrderQueryParamsModel = create_ordering_query_model_class(
         ordering_fields={"modified", "name"},
         default=OrderBy(field=IDStr("modified"), direction=OrderDirection.DESC),
     )
diff --git a/packages/service-library/tests/aiohttp/test_requests_validation.py b/packages/service-library/tests/aiohttp/test_requests_validation.py
index 7f395bfd654..97c2b317b6a 100644
--- a/packages/service-library/tests/aiohttp/test_requests_validation.py
+++ b/packages/service-library/tests/aiohttp/test_requests_validation.py
@@ -15,7 +15,7 @@
 from models_library.rest_ordering import (
     OrderBy,
     OrderDirection,
-    create_ordering_query_model_classes,
+    create_ordering_query_model_class,
 )
 from pydantic import BaseModel, ConfigDict, Field
 from servicelib.aiohttp import status
@@ -365,7 +365,7 @@ async def test_parse_request_with_invalid_headers_params(
 
 def test_parse_request_query_parameters_as_with_order_by_query_models():
 
-    OrderQueryModel = create_ordering_query_model_classes(
+    OrderQueryModel = create_ordering_query_model_class(
         ordering_fields={"modified", "name"}, default=OrderBy(field="name")
     )
 
@@ -376,4 +376,5 @@ def test_parse_request_query_parameters_as_with_order_by_query_models():
     request = make_mocked_request("GET", path=f"{url}")
 
     query_params = parse_request_query_parameters_as(OrderQueryModel, request)
-    assert query_params.order_by.model_dump() == expected.model_dump()
+
+    assert OrderBy.model_construct(**query_params.order_by.model_dump()) == expected
diff --git a/services/web/server/src/simcore_service_webserver/folders/_folders_handlers.py b/services/web/server/src/simcore_service_webserver/folders/_folders_handlers.py
index eb72dfeffee..becf8af0054 100644
--- a/services/web/server/src/simcore_service_webserver/folders/_folders_handlers.py
+++ b/services/web/server/src/simcore_service_webserver/folders/_folders_handlers.py
@@ -10,7 +10,6 @@
 from models_library.rest_ordering import OrderBy
 from models_library.rest_pagination import Page
 from models_library.rest_pagination_utils import paginate_data
-from pydantic import TypeAdapter
 from servicelib.aiohttp import status
 from servicelib.aiohttp.requests_validation import (
     parse_request_body_as,
@@ -82,7 +81,7 @@ async def list_folders(request: web.Request):
         trashed=query_params.filters.trashed,
         offset=query_params.offset,
         limit=query_params.limit,
-        order_by=OrderBy.model_validate(query_params.order_by),
+        order_by=OrderBy.model_construct(**query_params.order_by.model_dump()),
     )
 
     page = Page[FolderGet].model_validate(
@@ -121,7 +120,7 @@ async def list_folders_full_search(request: web.Request):
         trashed=query_params.filters.trashed,
         offset=query_params.offset,
         limit=query_params.limit,
-        order_by=TypeAdapter(OrderBy).validate_python(query_params.order_by),
+        order_by=OrderBy.model_construct(**query_params.order_by.model_dump()),
     )
 
     page = Page[FolderGet].model_validate(
diff --git a/services/web/server/src/simcore_service_webserver/folders/_models.py b/services/web/server/src/simcore_service_webserver/folders/_models.py
index f2e23f58ea6..9cac8a2f1a1 100644
--- a/services/web/server/src/simcore_service_webserver/folders/_models.py
+++ b/services/web/server/src/simcore_service_webserver/folders/_models.py
@@ -8,7 +8,7 @@
 from models_library.rest_ordering import (
     OrderBy,
     OrderDirection,
-    create_ordering_query_model_classes,
+    create_ordering_query_model_class,
 )
 from models_library.rest_pagination import PageQueryParameters
 from models_library.trash import RemoveQueryParams
@@ -42,7 +42,7 @@ class FolderFilters(Filters):
     )
 
 
-_FolderOrderQueryParams: type[RequestParameters] = create_ordering_query_model_classes(
+_FolderOrderQueryParams: type[RequestParameters] = create_ordering_query_model_class(
     ordering_fields={
         "modified_at",
         "name",
diff --git a/services/web/server/src/simcore_service_webserver/projects/_crud_handlers.py b/services/web/server/src/simcore_service_webserver/projects/_crud_handlers.py
index 12ce6bb6c18..95e35582c9e 100644
--- a/services/web/server/src/simcore_service_webserver/projects/_crud_handlers.py
+++ b/services/web/server/src/simcore_service_webserver/projects/_crud_handlers.py
@@ -203,7 +203,7 @@ async def list_projects(request: web.Request):
         limit=query_params.limit,
         offset=query_params.offset,
         search=query_params.search,
-        order_by=OrderBy.model_validate(query_params.order_by),
+        order_by=OrderBy.model_construct(**query_params.order_by.model_dump()),
         folder_id=query_params.folder_id,
         workspace_id=query_params.workspace_id,
     )
@@ -241,7 +241,7 @@ async def list_projects_full_search(request: web.Request):
         limit=query_params.limit,
         offset=query_params.offset,
         text=query_params.text,
-        order_by=query_params.order_by,
+        order_by=OrderBy.model_construct(**query_params.order_by.model_dump()),
         tag_ids_list=tag_ids_list,
     )
 
diff --git a/services/web/server/src/simcore_service_webserver/projects/_crud_handlers_models.py b/services/web/server/src/simcore_service_webserver/projects/_crud_handlers_models.py
index ba0ef6ae78f..5d10df1ffe1 100644
--- a/services/web/server/src/simcore_service_webserver/projects/_crud_handlers_models.py
+++ b/services/web/server/src/simcore_service_webserver/projects/_crud_handlers_models.py
@@ -15,7 +15,7 @@
 from models_library.rest_ordering import (
     OrderBy,
     OrderDirection,
-    create_ordering_query_model_classes,
+    create_ordering_query_model_class,
 )
 from models_library.rest_pagination import PageQueryParameters
 from models_library.utils.common_validators import (
@@ -100,7 +100,7 @@ class ProjectFilters(Filters):
     )
 
 
-ProjectsListOrderParams = create_ordering_query_model_classes(
+ProjectsListOrderParams = create_ordering_query_model_class(
     ordering_fields={
         "type",
         "uuid",
diff --git a/services/web/server/src/simcore_service_webserver/resource_usage/_service_runs_handlers.py b/services/web/server/src/simcore_service_webserver/resource_usage/_service_runs_handlers.py
index 73c75038d52..4f952a932de 100644
--- a/services/web/server/src/simcore_service_webserver/resource_usage/_service_runs_handlers.py
+++ b/services/web/server/src/simcore_service_webserver/resource_usage/_service_runs_handlers.py
@@ -16,7 +16,7 @@
 from models_library.rest_ordering import (
     OrderBy,
     OrderDirection,
-    create_ordering_query_model_classes,
+    create_ordering_query_model_class,
 )
 from models_library.rest_pagination import Page, PageQueryParameters
 from models_library.rest_pagination_utils import paginate_data
@@ -53,7 +53,7 @@ async def wrapper(request: web.Request) -> web.StreamResponse:
 
 _ResorceUsagesListOrderQueryParams: type[
     RequestParameters
-] = create_ordering_query_model_classes(
+] = create_ordering_query_model_class(
     ordering_fields={
         "wallet_id",
         "wallet_name",
@@ -136,7 +136,7 @@ async def list_resource_usage_services(request: web.Request):
         wallet_id=query_params.wallet_id,
         offset=query_params.offset,
         limit=query_params.limit,
-        order_by=OrderBy.model_validate(query_params.order_by),
+        order_by=OrderBy.model_construct(**query_params.order_by.model_dump()),
         filters=TypeAdapter(ServiceResourceUsagesFilters | None).validate_python(
             query_params.filters
         ),
@@ -216,7 +216,7 @@ async def export_resource_usage_services(request: web.Request):
         user_id=req_ctx.user_id,
         product_name=req_ctx.product_name,
         wallet_id=query_params.wallet_id,
-        order_by=TypeAdapter(OrderBy | None).validate_python(query_params.order_by),
+        order_by=OrderBy.model_construct(**query_params.order_by.model_dump()),
         filters=TypeAdapter(ServiceResourceUsagesFilters | None).validate_python(
             query_params.filters
         ),
diff --git a/services/web/server/src/simcore_service_webserver/workspaces/_models.py b/services/web/server/src/simcore_service_webserver/workspaces/_models.py
index fec1d7d8fcb..362d68884c7 100644
--- a/services/web/server/src/simcore_service_webserver/workspaces/_models.py
+++ b/services/web/server/src/simcore_service_webserver/workspaces/_models.py
@@ -6,7 +6,7 @@
 from models_library.rest_ordering import (
     OrderBy,
     OrderDirection,
-    create_ordering_query_model_classes,
+    create_ordering_query_model_class,
 )
 from models_library.rest_pagination import PageQueryParameters
 from models_library.trash import RemoveQueryParams
@@ -31,7 +31,7 @@ class WorkspacesPathParams(StrictRequestParameters):
 
 _WorkspacesListOrderQueryParams: type[
     RequestParameters
-] = create_ordering_query_model_classes(
+] = create_ordering_query_model_class(
     ordering_fields={
         "modified_at",
         "name",
diff --git a/services/web/server/src/simcore_service_webserver/workspaces/_workspaces_handlers.py b/services/web/server/src/simcore_service_webserver/workspaces/_workspaces_handlers.py
index fb2f7c9f1f6..9889e286dda 100644
--- a/services/web/server/src/simcore_service_webserver/workspaces/_workspaces_handlers.py
+++ b/services/web/server/src/simcore_service_webserver/workspaces/_workspaces_handlers.py
@@ -79,7 +79,7 @@ async def list_workspaces(request: web.Request):
         filter_trashed=query_params.filters.trashed,
         offset=query_params.offset,
         limit=query_params.limit,
-        order_by=OrderBy.model_validate(query_params.order_by),
+        order_by=OrderBy.model_construct(**query_params.order_by.model_dump()),
     )
 
     page = Page[WorkspaceGet].model_validate(
diff --git a/services/web/server/tests/unit/with_dbs/02/test_projects_crud_handlers__list_with_query_params.py b/services/web/server/tests/unit/with_dbs/02/test_projects_crud_handlers__list_with_query_params.py
index abb26a3f3e3..16610b9c774 100644
--- a/services/web/server/tests/unit/with_dbs/02/test_projects_crud_handlers__list_with_query_params.py
+++ b/services/web/server/tests/unit/with_dbs/02/test_projects_crud_handlers__list_with_query_params.py
@@ -7,9 +7,10 @@
 import json
 import random
 from collections import UserDict
+from collections.abc import Iterator
 from copy import deepcopy
 from pathlib import Path
-from typing import Any, Iterator
+from typing import Any
 
 import pytest
 import sqlalchemy as sa