Merge pull request #6496 from gmndrg/main

Update search-howto-concurrency.md

Author: prmerger-automator[bot]

articles/search/search-howto-concurrency.md

@@ -7,7 +7,7 @@ author: HeidiSteen
 ms.author: heidist
 ms.service: azure-ai-search
 ms.topic: how-to
-ms.date: 07/11/2025
+ms.date: 08/08/2025
 ms.custom:
   - devx-track-csharp
   - ignite-2023
@@ -32,6 +32,8 @@ Every time you update a resource, its ETag changes automatically. When you imple
 > [!Note]
 > There is only one mechanism for concurrency. It's always used regardless of which API or SDK is used for resource updates.
 
+Starting July 18, 2025, Azure AI Search began enforcing serialization for index creation and update operations to ensure consistency and reliability. This change aligns with long-standing best practices and the established behavior of the rest of operations in the service. As the rollout progresses across regions, you may begin seeing 409 conflict errors when sending concurrent or closely timed requests. To avoid these errors, ensure operations are not sent in parallel and follow the concurrency guidance outlined in this document.
+
 ## Example
 
 The following code demonstrates optimistic concurrency for an update operation. It fails the second update because the object's ETag is changed by a previous update. More specifically, when the ETag in the request header no longer matches the ETag of the object, the search service return a status code of 400 (bad request), and the update fails.