kb5078752-x64 failing with 0x80073701 - ERROR_SXS_ASSEMBLY_MISSING

Hi Mike Malko,

The error code 0x80073701 translates to ERROR_SXS_ASSEMBLY_MISSING, which indicates your server's WinSxS directory is missing required component payloads to complete the update process. You should never manually alter permissions on the WinSxS folder, as this will permanently damage the servicing stack. To repair the component store properly, you need to use the Deployment Image Servicing and Management tool alongside a known-good source file. Mount a Windows Server 2019 ISO that matches your current OS edition, open an elevated command prompt, and run a RestoreHealth command specifying the install.wim file within the mounted ISO's sources folder as your target source. This approach forces Windows to bypass the standard update channels and pull uncorrupted system files directly from the original installation media.

If the cumulative update installation still fails after running the repair tool, you will need to identify the exact missing system component by analyzing your CBS log file. Navigate to the C:\Windows\Logs\CBS directory and open the CBS.log text file immediately after the update fails. Search the document for the 0x80073701 error code or the missing manifest phrase to find the specific package identifier the system is struggling to locate. Once identified, you can often download that missing prerequisite update directly from the Microsoft Update Catalog and install it manually to bridge the gap in your component store.

Should the corruption prove completely unrepairable by DISM and manual package installation, you must consider the safest path forward for a Domain Controller. While in-place OS upgrades are technically supported by Microsoft, they carry unnecessary risk for critical Active Directory infrastructure when servicing stack corruption is already present. The established enterprise best practice is to deploy a fresh Windows Server 2019 virtual machine, promote it to a Domain Controller within your existing domain, transfer all Flexible Single Master Operations roles to the new machine, and finally perform a graceful demotion of the corrupted server.

Hope this answer brought you some useful information. If it did, please hit “accept answer”. Should you have any questions, feel free to leave a comment.

VP

Error 0x80073701 (ERROR_SXS_ASSEMBLY_MISSING) indicates component store corruption or missing manifests that the update depends on.

On a Windows Server 2019 domain controller, use the same servicing stack repair approach as for other Windows Server/Windows 10 systems:

1. Run a full DISM health check and repair
   1. Open an elevated Command Prompt.
   2. Run these commands in order:

            DISM /ONLINE /CLEANUP-IMAGE /SCANHEALTH
            DISM /ONLINE /CLEANUP-IMAGE /CHECKHEALTH
            DISM /ONLINE /CLEANUP-IMAGE /RESTOREHEALTH
            SFC /SCANNOW
      

   3. Restart the server.
   4. Try installing KB5078752 again.
2. If the error persists and CBS.log shows missing manifests or packages Error 0x80073701 is similar in nature to 0x800f0831 and 0x80070002 cases where the component store is missing payloads or DLLs. In that situation:
   1. Review C:\Windows\Logs\CBS\CBS.log for entries about missing packages or files (for example, “manifest missing for package” or specific DLLs under WinSxS).
   2. If CBS indicates a specific missing package (similar to the 0x800f0831 scenario):
      • Go to the Microsoft Update Catalog.
      • Search for the package ID reported as missing.
      • Download the update that matches the OS build and architecture.
      • Install the downloaded package manually.
   3. If CBS indicates missing DLLs in C:\Windows\WinSxS (similar to the 0x80070002 scenario):
      • Identify the missing DLLs from CBS.log.
      • Source the same files from a healthy Server 2019 machine at the same patch level.
      • Take ownership and grant permissions on C:\Windows\WinSxS:

                takeown /f c:\windows\winsxs
                icacls c:\windows\winsxs /grant administrators:F
                cd c:\windows\winsxs
        

      • Create the exact folder path for the missing DLL and copy the DLL into it, for example:

                mkdir <folder_name_from_CBS_log>
                copy c:\windows\temp\<dllname>.dll c:\windows\winsxs\<folder_name_from_CBS_log>
        

      • Then run:

                DISM.exe /Online /Cleanup-image /Restorehealth
        

      • Retry installing KB5078752 (preferably from its standalone package via Microsoft Update Catalog).
3. If repeated attempts still fail If DISM/RestoreHealth and manual payload repair do not resolve the missing assemblies, an in-place repair/upgrade of the OS (using the matching Server 2019 ISO) is typically required to fully rebuild the component store before attempting the cumulative update again.

References:

• Error 0x800f0831 when you install an update
• Troubleshoot Windows Update error 0x80070002
• When trying to install updates from Windows Update you might receive "Updates Failed. There were problems installing some updates, but we'll try again later" with Errors: 0x80073701, 0x800f0988