SharePoint 2019 Language Pack KB5002774 Installation Fails – Missing .deploy File

Hi all,

We are encountering issues while installing the KB5002774 language pack update on a SharePoint 2019 Server. The installation fails with an error referencing with permissions issues, or specific mention of a missing file.

Initial Event:
Product: Microsoft SharePoint Server 2019 1033 Language Pack - Update 'Security Update for Microsoft SharePoint Server 2019 Language Pack (KB5002774)' could not be installed. Error code 1603. 

Second Event:
Product: Microsoft SharePoint Server 2019 1033 Language Pack -- Error 1310. Error writing to file: C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\TEMPLATE\LAYOUTS\ddm\1033\ddm\DDManager.exe.deploy.  System error 0.  Verify that you have access to that directory.

Environment: SharePoint version: 2019, Windows Server 2019

Update: KB5002774 (September 2025 Language Pack Security Update)
Language pack: English (1033)
Installation method: Manual via Microsoft Update Catalog

What We've Tried:
- Verified that the base SharePoint 2019 installation is healthy and patched, KB5002775 successfully installed and applied.
- Checked the folders and subfolders, permissions are at Full Control - DDManager.exe.deploy is missing but other files exist at that location.
- Verified account permissions, folder/file permissions, re-download and attempted reapply of the update (3x).

Questions:
- Is DDManager.exe.deploy part of the official KB5002774 package, or is it installed from another source/patch/package?
- Has anyone else encountered this issue with KB5002774 or other language pack updates?
- Is there a safe workaround to bypass or restore this file to allow the update to complete?

Any insights or suggestions other would be appreciated.

Thank you in advance.