I have a Windows Server 2019 system that has not been updated since 2021. Windows Update now offers a current cumulative update, but every installation attempt fails with error 0x80073701. I already ran DISM /Online /Cleanup-Image /StartComponentCleanup and rebooted, but the problem remains.
The CBS log reports ERROR_SXS_ASSEMBLY_MISSING while trying to resolve packages such as KB5003646 and the servicing stack. What additional logs or repair steps should I try to get this server updating again?
3 Answers
Run the component repair with a known-good installation source instead of using only the local component store. Mount matching Windows Server 2019 media and use DISM with the appropriate install.wim or install.esd source, for example: DISM /Online /Cleanup-Image /RestoreHealth /Source:wim:X:sourcesinstall.wim: /LimitAccess. The source must match the installed build and language. Afterward run sfc /scannow, reboot, and retry the servicing stack and cumulative updates.
The CBS.log is the right place to investigate. Also review DISM.log and the Windows Update log generated with Get-WindowsUpdateLog, and search for the first missing assembly or package error rather than only the final 0x80073701 result. If repairing the component store and manually applying the SSU still fails, an in-place repair upgrade using matching Server 2019 media may be safer than repeatedly forcing individual updates.
The CBS entries confirm that a required side-by-side assembly is missing, rather than this being a normal Windows Update download problem. Since the server has been unattended for several years, first install the latest applicable servicing stack update for Windows Server 2019 manually from the Microsoft Update Catalog, then install the latest cumulative update. Reboot between packages and verify that the update matches the server's build, architecture, language, and edition.
The CBS log shows ERROR_SXS_ASSEMBLY_MISSING for a package associated with an older update, so I will check the servicing stack history and try a matching repair source before attempting the current cumulative update again.