September 2025 CU for SharePoint Server 2019 is available for download

- - 27 Comments

The product group released the September 2025 Cumulative Update for SharePoint Server 2019 product family. SharePoint Server 2019 is patched with a language dependent and a language independent fix.

The KB article for September 2025 CU will be available at the following Location in a couple of hours:

  • KB 5002775 – September 2025 Update for SharePoint Server 2019 (language independent)
    This is also a security update!
  • KB 5002774 – September 2025 Update for SharePoint Server 2019 (language dependent)
    This is also a security update!

The downloads for September 2025 CU are available through the following links:

Important: It is required to install both fixes (language dependent and independent) to fully patch a SharePoint server. This applies also to servers which do not have language packs installed. The reason is that each SharePoint installation includes a language dependent component together with a language independent component. If additional language packs are added later (only) the language dependent fix has to be applied again.

It is irrelevant which language you pick on the drop down in download center. Even the language dependent fixes are all in the same package for all languages.

After installing the fixes you need to run the SharePoint 2019 Products Configuration Wizard on each machine in the farm. If you prefer to run the command line version psconfig.exe ensure to have a look here for the correct options.

Please ensure to have a look at the SharePoint Patching Best Practices before applying new fixes.

 
SharePoint 2019 September 2025 CU Build Number:

Language independent fix: 16.0.10417.20047
Language dependent fix: 16.0.10417.20047
 

Related Links:

27 Comments


  1. Hey Stefan,

    The KB states “in order to use workflows in SharePoint Server, you must now have the latest update for SharePoint Workflow Manager installed.”

    If we are currently using Workflow Manager (the version prior to SharePoint Workflow Manager) does that mean that our current workflows will stop working if we apply the Sept CU?

    Thanks in advance.

    Reply

    1. Hi Daniel,
      I had the same idea but when I checked the details the code path is not executed for classic workflow manager.
      There should not be an issue.
      We did some tests meanwhile – and indeed classic workflow manager does not longer work with September 2025 CU for SharePoint.
      Only SharePoint Workflow Manager with latest CU is working
      Cheers,
      Stefan

      Reply

      1. Thank you for all your help over the years, Stefan. We have a SharePoint Workflow Manager Server stood up and we are preparing for a cutover. Would we then need to copy the assemblies from the SharePoint 2019 server register them to the GAC on the SharePoint Workflow Manager Server similar to how the Subscription Edition is after the August 2025 CU?

        Thanks again in advance.

        Reply

  2. Hi Stefan,

    You are writing “August cumulative updates”, but on the KB page at Microsoft they are September, obviously. Is it a mistype in your post?

    Thanks,
    Jevgenij

    Reply

    1. Hi Jevgenij,
      thanks for the heads-up! Was indeed incorrect. Fixed it.
      Cheers,
      Stefan

      Reply

  3. Hi.

    I have issue on my dev server that I encountered for the first time in 5 years of patching this server:

    Failed to complete the SharePoint Products configuration.
    An exception of type System.InvalidOperationException was thrown. Additional exception information: An internal error occurred. The program cannot continue to run. The program stopped because of the following: Copy SideBySide files for In Place Upgrade failed.
    System.InvalidOperationException: An internal error occurred. The program cannot continue to run. The program stopped because of the following: Copy SideBySide files for In Place Upgrade failed.
    at Microsoft.SharePoint.PostSetupConfiguration.Common.ThrowNewInvalidOperationException(String exceptionData)
    at Microsoft.SharePoint.PostSetupConfiguration.FinalizeTask.Run()
    at Microsoft.SharePoint.PostSetupConfiguration.TaskThread.ExecuteTask()

    When I go to central admin it shows as succeeded but when I run psconfig:
    09/10/2025 13:11:21 1 ERR Failed to complete the SharePoint Products configuration.
    An exception of type System.InvalidOperationException was thrown. Additional exception information: An internal error occurred. The program cannot continue to run. The program stopped because of the following: Copy SideBySide files for In Place Upgrade failed.
    System.InvalidOperationException: An internal error occurred. The program cannot continue to run. The program stopped because of the following: Copy SideBySide files for In Place Upgrade failed.
    at Microsoft.SharePoint.PostSetupConfiguration.Common.ThrowNewInvalidOperationException(String exceptionData)
    at Microsoft.SharePoint.PostSetupConfiguration.FinalizeTask.Run()
    at Microsoft.SharePoint.PostSetupConfiguration.TaskThread.ExecuteTask()

    Any idea what am I doing wrong?

    Thanks!

    Reply

    1. Hi Grega,
      I would suggest to run the Copy-SPSideBySideFiles CmdLet in the SharePoint Management Shell manually and check if this works.
      Also check which account you used to run the configuration wizard. The account should not be used as an application pool account as this adds it to the WSS_WPG group which has restricted rights starting with this CU.
      Cheers,
      Stefan

      Reply

      1. Hi,
        seen this issue in our setup of Sharepoint 2019 as well. There is deny permssion of “..\Web Server Extensions\16\template\Layouts” folder for WSS_WPG and IIS_IUSRS Group. As far as i know Sharepoint Farm Account needs to be inside WSS_WPG group, therefore upgrade procedure fails.

        Question remains: Misconfiguraion or bug due to recent security incidents?
        Best,
        Timo

        Reply

          1. Hi Stefan,
            thanks for the followup – much appreciatetd. Will make sure to get the configuration compliant.

            Speaking of compliant, Workflow Manager (not Sharepoint Workflow Manager) seems to be broken as of September 2025 CU, any information about this? Seen you weren’t sure about this if i understand correctly but maybe there is new information you recevied?
            Best,
            Timo


          2. Hi Timo,
            ok, that’s interesting.
            Best would be to open a ticket with Microsoft Support to get this investigated.
            Cheers,
            Stefan


      2. Hello,

        We have also encountered the same issue for the first time when applying a CU-patch. We tried running the Copy-SPSideBySideFiles CmdLet manually but that did not work either. We also tried running the Config Wizard with a service account that is not running any application pools, but it fails with the same error. We do get the “Successfully upgraded SharePoint….” but then the post step fails referring to the Copy Side by Side files.

        We have had the same issue in 3 different environments.

        Best Regards,
        Thomas

        Reply

      3. I ran into the same problem, Copy-SPSideBySideFiles fails aswell. I’ve always used the farm account to run the wizard but that no longer works. Farm still runs these pools:
        Sharepoint Web Service System
        The pool for the security token application
        What would be a suitable account to instead run those pools with instead of farm or should a different account to farm now be used to run the the final configuration?
        Thanks for your helpful blog!

        Reply

      4. Hi!

        “The account should not be used as an application pool account as this adds it to the WSS_WPG group which has restricted rights starting with this CU”

        Spot on, thank you very much!
        PROD has this configured OK, but on DEV I used shortcut and used farm_dev_admin for IIS pools as well.

        Thanks again and hope this helps someone else too!

        Finalizing the upgrade…

        Successfully upgraded SharePoint Products.

        Performing configuration task 8 of 8
        Finalizing the SharePoint Products configuration…

        Successfully completed the SharePoint Products configuration.

        Total number of configuration settings run: 8
        Total number of successful configuration settings: 8
        Total number of unsuccessful configuration settings: 0

        Reply

  4. Hi,

    Installing the language pack throws me this error in 2 environments:

    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\ppsma\1033\DesignerInstall\en\Microsoft.PerformancePoint.Scorecards.DesignerPlugins.dll.deploy. System error 0. Verify that you have access to that directory.

    The directory looks fine and there is no file with this name in it. Any idea?

    Reply

    2. we are seeing the same thing and what i have found so far is the group WSS_WPG has NT AUTHORITY\local system as a member. If you install the base sharepoint CU/psconfig only and then the language update the base CU process is changing the NTFS rights on the folder path “C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\TEMPLATE\LAYOUTS\” and setting the WSS_WPG group from allow to deny write to this folder and sub folders. the issue being this breaks windows installer that runs as the local system account. temporarily removing the NT AUTHORITY\local system membership from the group, reboot and running the language update will succeeded. running ps config again will update the WSS_WPG group and add the back NT AUTHORITY\local system.

      Reply

      1. Hi CM,
        NT AUTHORITY\local system should never be a member of WSS_WPG.
        It sounds as if you are running a SharePoint Service or application pool with this identity.
        This should be flagged in a health rule.
        Ensure to change the relevant assignments and remove this identity from the WSS_WPG group.
        Cheers,
        Stefan

        Reply

  5. Hi CM!
    Thanks for the hint. I can confirm this allows to install the Language Pack.
    After running the PSCONFIG the accounts are re-added to the WSS_WPG group.

    Reply

    1. Hi ZG,
      that means you most likely used this account as managed account or as application pool account in SharePoint.
      Please fix this and remove local system here.
      Cheers,
      Stefan

      Reply

  6. Hey Stefan, we have our application pools and services running under either ApplicationPoolIdentity or a custom Service Account but NT Authority\Local Service and System are in the WSS_WPG group. Do we need to remove both or just System before installing the September 2025 CU? Thank you.

    Reply

  7. Hi Stefan,

    Thank you for the updates. looks like there are multiple issues have been raised following the September 2025 Cumulative Update. Is Microsoft planning to release a new Cumulative Update soon to address these issues? If there is a possibility of a new release in the next few days, we will wait; otherwise, we will proceed with installing the current release and continue troubleshooting as needed

    Best Regards,
    Karthik Arvapalli

    Reply

    1. Hi Karthik,
      CUs are released on a monthly cadence. Next CU will be October 2025 CU and some of the issues might be addressed there.
      Cheers,
      Stefan

      Reply

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