diff --git a/apps/wpm/serializers.py b/apps/wpm/serializers.py
index 0254db34..558d805d 100644
--- a/apps/wpm/serializers.py
+++ b/apps/wpm/serializers.py
@@ -828,7 +828,7 @@ class MlogbInUpdateSerializer(CustomModelSerializer):
         return ins
     
 class MlogbwCreateUpdateSerializer(CustomModelSerializer):
-    ftest = FtestProcessSerializer(required=False)
+    ftest = FtestProcessSerializer(required=False, allow_null=True)
     equip_name = serializers.CharField(source='equip.name', read_only=True)
     equip_number = serializers.CharField(source='equip.number', read_only=True)
     class Meta: