diff --git a/backend/infrahub/core/schema/node_schema.py b/backend/infrahub/core/schema/node_schema.py
index b6645fad13..a642ef5964 100644
--- a/backend/infrahub/core/schema/node_schema.py
+++ b/backend/infrahub/core/schema/node_schema.py
@@ -41,12 +41,18 @@ def validate_inheritance(self, interface: GenericSchema) -> None:
                     raise ValueError(
                         f"{self.kind}'s attribute {attribute.name} inherited from {interface.kind} cannot be overriden"
                     )
+
+                interface_attr = interface.get_attribute(attribute.name)
                 # Check existing inherited attribute kind is the same as the incoming inherited attribute
-                interface_attr_kind = interface.get_attribute(attribute.name).kind
-                if attribute.kind != interface_attr_kind:
+                if attribute.kind != interface_attr.kind:
                     raise ValueError(
                         f"{self.kind}.{attribute.name} inherited from {interface.namespace}{interface.name} must be the same kind "
-                        f'["{interface_attr_kind}", "{attribute.kind}"]'
+                        f'["{interface_attr.kind}", "{attribute.kind}"]'
+                    )
+                if attribute.optional != interface_attr.optional:
+                    raise ValueError(
+                        f"{self.kind}.{attribute.name} inherited from {interface.namespace}{interface.name} must have the same value for property "
+                        f'"optional" ["{interface_attr.optional}", "{attribute.optional}"]'
                     )
 
         for relationship in self.relationships:
diff --git a/backend/tests/unit/core/schema_manager/test_manager_schema.py b/backend/tests/unit/core/schema_manager/test_manager_schema.py
index bcbf8a9a7c..1b1f4bce9c 100644
--- a/backend/tests/unit/core/schema_manager/test_manager_schema.py
+++ b/backend/tests/unit/core/schema_manager/test_manager_schema.py
@@ -146,6 +146,26 @@ async def test_schema_process_inheritance_different_generic_attribute_types_on_n
     assert exc.value.args[0] == 'TestWidget.choice inherited from TestAdapter must be the same kind ["Text", "List"]'
 
 
+async def test_schema_process_inheritance_different_generic_attribute_optional_on_node(
+    schema_diff_attr_inheritance_types,
+):
+    """Test that we raise an exception if a node is inheriting an attribute changing its optional property value."""
+    schema = SchemaBranch(cache={}, name="test")
+    schema_new = copy.deepcopy(schema_diff_attr_inheritance_types)
+    schema_new["generics"].pop()
+    schema_new["nodes"][0]["inherit_from"].pop()
+    schema_new["nodes"][0]["attributes"].append({"name": "choice", "kind": "Text", "optional": False})
+    schema.load_schema(schema=SchemaRoot(**schema_new))
+
+    with pytest.raises(ValueError) as exc:
+        schema.process_inheritance()
+
+    assert (
+        exc.value.args[0]
+        == 'TestWidget.choice inherited from TestAdapter must have the same value for property "optional" ["True", "False"]'
+    )
+
+
 async def test_schema_branch_process_inheritance_node_level(animal_person_schema_dict):
     schema = SchemaBranch(cache={}, name="test")
     schema.load_schema(schema=SchemaRoot(**animal_person_schema_dict))
diff --git a/changelog/4936.fixed.md b/changelog/4936.fixed.md
new file mode 100644
index 0000000000..c1093a288a
--- /dev/null
+++ b/changelog/4936.fixed.md
@@ -0,0 +1 @@
+Forbid changing the "optional" property of an inherited attribute to not break GraphQL schema generation
\ No newline at end of file