diff --git a/src/backend/InvenTree/InvenTree/api_version.py b/src/backend/InvenTree/InvenTree/api_version.py
index 200c2be075..cf182612b5 100644
--- a/src/backend/InvenTree/InvenTree/api_version.py
+++ b/src/backend/InvenTree/InvenTree/api_version.py
@@ -1,11 +1,14 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 351
+INVENTREE_API_VERSION = 352
 
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 INVENTREE_API_TEXT = """
+v352 -> 2025-06-18 : https://github.com/inventree/InvenTree/pull/9803
+    - Make PurchaseOrderLineItem link to BuildOrder reference nullable
+    - Add valid fields to ordering field descriptions
 
 v351 -> 2025-06-18 : https://github.com/inventree/InvenTree/pull/9602
     - Adds passwort reset API endpoint for admin users
diff --git a/src/backend/InvenTree/InvenTree/schema.py b/src/backend/InvenTree/InvenTree/schema.py
index f051af08e2..1999b102ca 100644
--- a/src/backend/InvenTree/InvenTree/schema.py
+++ b/src/backend/InvenTree/InvenTree/schema.py
@@ -91,6 +91,16 @@ class ExtendedAutoSchema(AutoSchema):
                 if parameter['name'] == 'limit':
                     parameter['required'] = True
 
+        # Add valid order selections to the ordering field description.
+        ordering_fields = getattr(self.view, 'ordering_fields', None)
+        if ordering_fields is not None:
+            parameters = operation.get('parameters', [])
+            for parameter in parameters:
+                if parameter['name'] == 'ordering':
+                    parameter['description'] = (
+                        f'{parameter["description"]} Possible fields: {", ".join(ordering_fields)}.'
+                    )
+
         return operation
 
 
diff --git a/src/backend/InvenTree/order/serializers.py b/src/backend/InvenTree/order/serializers.py
index f49af7ae8a..86339c39ae 100644
--- a/src/backend/InvenTree/order/serializers.py
+++ b/src/backend/InvenTree/order/serializers.py
@@ -649,7 +649,7 @@ class PurchaseOrderLineItemSerializer(
     )
 
     build_order_detail = build.serializers.BuildSerializer(
-        source='build_order', read_only=True, many=False
+        source='build_order', read_only=True, allow_null=True, many=False
     )
 
     merge_items = serializers.BooleanField(