April 2021 CU for SharePoint Server 2019 is available for download

The product group released the April 2021 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 April 2021 CU will be available at the following Location in a couple of hours:

  • KB 4504716 – April 2021 Update for SharePoint Server 2019 (language independent) – This is also a security update!
  • KB 4504715 – April 2021 Update for SharePoint Server 2019 (language dependent) – This is also a security update!

The download for April 2021 CU is available through the following link:

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 April 2021 CU Build Number:

Language independent fix: 16.0.10373.20000
Language dependent fix: 16.0.10373.20000

Related Links:


  1. Is anyone else missing the left navigation after applying this patch?


    1. Clearing the cache for Edge resolved the issue. It only affected modern pages.


  2. After applying this CU, we are unable to view Modern list/libraries in our environment. We are getting this message:

    “Cannot make a cache safe URL for “next/odspnext/en-us/splistreactcontrolsbeforeplt.resx.js”, file not found. Please verify that the file exists under the layouts directory.”

    When the list/library is switched back to Classic, it starts working again. The only suggested resolution I found so far was to install Security Update for Microsoft SharePoint Server 2019 Language Pack (KB4493161).

    I haven’t tried the suggested fix yet; just curious if anybody else has experienced the issue.


    1. Hi Marvin,
      if you installed 4504715 from April CU you will not be able to install 4493161 as this is an older version of the same package.
      Please double check that you successfully installed both patches from April CU (4504715 and 4504716)


  3. After applying this CU, we are having issues sending mails in different locations.
    We are getting access denied.
    Is anybody else seeing this?


  4. In a Doc-Libary as long as the [details pane] is open, no actions such as renaming, deleting or editing and and can be performed. Is this known? any solutions? is May CU a solution?


  5. Same problem, Modern list, libraries doesnt work anymore.

    Error:Sorry, something went wrong
    Cannot make a cache safe URL for “next/odspnext/en-us/splistreactcontrolsbeforeplt.resx.js”, file not found. Please verify that the file exists under the layouts directory.


    1. Hi Kim,
      this error can occur if you installed only the language independent fix without installing the language dependent one. Please ensure that the language dependent fix is applied and the configuration wizard was run after installing the fixes.


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