diff --git a/flow360/component/simulation/framework/updater.py b/flow360/component/simulation/framework/updater.py
index 7086efd1a..f8ce82586 100644
--- a/flow360/component/simulation/framework/updater.py
+++ b/flow360/component/simulation/framework/updater.py
@@ -24,6 +24,8 @@
 from flow360.log import log
 from flow360.version import __version__
 
+DEFAULT_PLANAR_FACE_TOLERANCE = 1e-6
+
 
 def _to_24_11_1(params_as_dict):
     # Check and remove the 'meshing' node if conditions are met
@@ -284,6 +286,17 @@ def _to_25_6_2(params_as_dict):
     return params_as_dict
 
 
+def _to_25_6_4(params_as_dict):
+    if params_as_dict.get("meshing") is None:
+        return params_as_dict
+    if "defaults" not in params_as_dict["meshing"]:
+        return params_as_dict
+    meshing_defaults = params_as_dict["meshing"].get("defaults", {})
+    if meshing_defaults.get("planar_face_tolerance") is None:
+        meshing_defaults["planar_face_tolerance"] = DEFAULT_PLANAR_FACE_TOLERANCE
+    return params_as_dict
+
+
 VERSION_MILESTONES = [
     (Flow360Version("24.11.1"), _to_24_11_1),
     (Flow360Version("24.11.7"), _to_24_11_7),
@@ -292,7 +305,8 @@ def _to_25_6_2(params_as_dict):
     (Flow360Version("25.2.1"), _to_25_2_1),
     (Flow360Version("25.2.3"), _to_25_2_3),
     (Flow360Version("25.4.1"), _to_25_4_1),
-    (Flow360Version("25.6.4"), _to_25_6_2),
+    (Flow360Version("25.6.2"), _to_25_6_2),
+    (Flow360Version("25.6.4"), _to_25_6_4),
 ]  # A list of the Python API version tuple with there corresponding updaters.
 
 
diff --git a/flow360/component/simulation/meshing_param/params.py b/flow360/component/simulation/meshing_param/params.py
index 99c9a4d61..d810ed2a2 100644
--- a/flow360/component/simulation/meshing_param/params.py
+++ b/flow360/component/simulation/meshing_param/params.py
@@ -7,6 +7,7 @@
 
 import flow360.component.simulation.units as u
 from flow360.component.simulation.framework.base_model import Flow360BaseModel
+from flow360.component.simulation.framework.updater import DEFAULT_PLANAR_FACE_TOLERANCE
 from flow360.component.simulation.meshing_param.edge_params import SurfaceEdgeRefinement
 from flow360.component.simulation.meshing_param.face_params import (
     BoundaryLayer,
@@ -105,7 +106,7 @@ class MeshingDefaults(Flow360BaseModel):
     )
 
     planar_face_tolerance: pd.NonNegativeFloat = pd.Field(
-        1e-6,
+        DEFAULT_PLANAR_FACE_TOLERANCE,
         description="Tolerance used for detecting planar faces in the input surface mesh / geometry"
         " that need to be remeshed, such as symmetry planes."
         " This tolerance is non-dimensional, and represents a distance"
diff --git a/flow360/component/simulation/models/surface_models.py b/flow360/component/simulation/models/surface_models.py
index 1dac5e4b1..8dae817c5 100644
--- a/flow360/component/simulation/models/surface_models.py
+++ b/flow360/component/simulation/models/surface_models.py
@@ -42,7 +42,7 @@
 from flow360.component.simulation.validation.validation_utils import (
     check_deleted_surface_in_entity_list,
     check_deleted_surface_pair,
-    check_symmetric_boundary_existence_for_inhouse,
+    check_symmetric_boundary_existence,
 )
 
 # pylint: disable=fixme
@@ -57,7 +57,7 @@ class EntityListAllowingGhost(EntityList):  # Define EntityList to include valid
     @classmethod
     def ghost_entity_validator(cls, value):
         """Run all validators"""
-        return check_symmetric_boundary_existence_for_inhouse(value)
+        return check_symmetric_boundary_existence(value)
 
 
 class BoundaryBase(Flow360BaseModel, metaclass=ABCMeta):
diff --git a/flow360/component/simulation/validation/validation_utils.py b/flow360/component/simulation/validation/validation_utils.py
index 6d6558c1e..3881eb3f2 100644
--- a/flow360/component/simulation/validation/validation_utils.py
+++ b/flow360/component/simulation/validation/validation_utils.py
@@ -117,7 +117,7 @@ def check_deleted_surface_pair(value):
     return value
 
 
-def check_symmetric_boundary_existence_for_inhouse(stored_entities):
+def check_symmetric_boundary_existence(stored_entities):
     """Check according to the criteria if the symmetric plane exists."""
     validation_info = get_validation_info()
 
diff --git a/tests/simulation/service/test_services_v2.py b/tests/simulation/service/test_services_v2.py
index add76f3c7..392c4737f 100644
--- a/tests/simulation/service/test_services_v2.py
+++ b/tests/simulation/service/test_services_v2.py
@@ -985,10 +985,7 @@ def test_front_end_JSON_with_multi_constructor():
 def test_generate_process_json():
     params_data = {
         "meshing": {
-            "defaults": {
-                # "boundary_layer_first_layer_thickness": "1*m",
-                # "surface_max_edge_length": "1*m",
-            },
+            "defaults": {},
             "volume_zones": [
                 {
                     "method": "auto",
@@ -1062,7 +1059,7 @@ def test_generate_process_json():
     with pytest.raises(
         ValueError,
         match=re.escape(
-            "[{'type': 'missing', 'loc': ('meshing', 'surface_max_edge_length'), 'msg': 'Field required', 'input': None, 'ctx': {'relevant_for': ['SurfaceMesh']}, 'url': 'https://errors.pydantic.dev/2.11/v/missing'}]"
+            "[{'type': 'missing', 'loc': ('meshing', 'defaults', 'surface_max_edge_length'), 'msg': 'Field required', 'input': None, 'ctx': {'relevant_for': ['SurfaceMesh']}, 'url': 'https://errors.pydantic.dev/2.11/v/missing'}]"
         ),
     ):
         res1, res2, res3 = services.generate_process_json(
diff --git a/tests/simulation/test_updater.py b/tests/simulation/test_updater.py
index 01cf3e105..f917bc8b5 100644
--- a/tests/simulation/test_updater.py
+++ b/tests/simulation/test_updater.py
@@ -494,7 +494,7 @@ def test_updater_to_25_6_2():
     def _update_to_25_6_2(pre_update_param_as_dict, version_from):
         params_new = updater(
             version_from=version_from,
-            version_to=f"25.6.4",
+            version_to=f"25.6.2",
             params_as_dict=pre_update_param_as_dict,
         )
         return params_new
@@ -711,3 +711,21 @@ def test_deserialization_with_updater():
         validated_by=ValidationCalledBy.LOCAL,
         validation_level=ALL,
     )
+
+
+def test_updater_to_25_6_4():
+    with open("../data/simulation/simulation_pre_25_4_1.json", "r") as fp:
+        params_as_dict = json.load(fp)
+
+    params_new = updater(
+        version_from="25.4.0b1",
+        version_to=f"25.6.4",
+        params_as_dict=params_as_dict,
+    )
+    assert params_new["meshing"]["defaults"]["planar_face_tolerance"] == 1e-6
+    params_new, _, _ = validate_model(
+        params_as_dict=params_new,
+        validated_by=ValidationCalledBy.LOCAL,
+        root_item_type="Geometry",
+    )
+    assert params_new