diff --git a/iothub/service/src/Common/Exceptions/ErrorCode.cs b/iothub/service/src/Common/Exceptions/ErrorCode.cs
index 994d90e489..d32e3db3c4 100644
--- a/iothub/service/src/Common/Exceptions/ErrorCode.cs
+++ b/iothub/service/src/Common/Exceptions/ErrorCode.cs
@@ -165,8 +165,10 @@ public enum ErrorCode
 
         ModuleAlreadyExistsOnDevice = 409301,
 
-        // PreconditionFailed - 412
-        PreconditionFailed = 412001,
+        /// <summary>
+        /// The etag in the request does not match the etag of the existing resource, as per <see href="https://datatracker.ietf.org/doc/html/rfc7232">RFC7232</see>. The etag is controlled by the service and is based on the device identity it should not be updated in normal operations. 
+        /// </summary>
+        PreconditionFailed = 412001, // PreconditionFailed - 412
 
         /// <summary>
         /// When a device receives a cloud-to-device message from the queue (for example, using ReceiveAsync())