diff --git a/MDM/Models/Process/Dto/ProcessOperationDto.cs b/MDM/Models/Process/Dto/ProcessOperationDto.cs
index 5607743..6ccff57 100644
--- a/MDM/Models/Process/Dto/ProcessOperationDto.cs
+++ b/MDM/Models/Process/Dto/ProcessOperationDto.cs
@@ -63,7 +63,7 @@ namespace MDM.Model.Process.Dto
 
         public int? Status { get; set; }
 
-        public string CreatedBy { get; set; }
+        public string? CreatedBy { get; set; }
 
         public DateTime? CreatedTime { get; set; }