I’m encountering an issue installing a Windows MSU patch (e.g., KBXXXXXXX) using WUSA on Windows 10. The initial installation phase completes successfully, but after restarting, the post-install phase reaches 94% on the blue screen and fails with the message: “We couldn’t complete the updates. Undoing changes. Don’t turn off your computer.” The system then reverts, and the update isn’t applied.
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No obvious errors in CBS.log, WindowsUpdate.log, or SetupAPI.dev.log. I’ve enabled verbose logging and used Get-WindowsUpdateLog to check ETL files, but nothing points to the cause.
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This happens consistently, even in Safe Mode.
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System health checks (DISM /RestoreHealth, SFC /scannow, CHKDSK /f /r) pass without issues.
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Reset Windows Update components (cleared SoftwareDistribution and Catroot2 folders).
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Tried manual installation via a PowerShell script that extracts the MSU (using expand.exe), identifies SSU and main CABs, checks if they’re already installed (via Get-Hotfix), and installs them one-by-one with DISM /Add-Package. The script logs everything, parses CBS for errors, and prompts for reboots. Even this fails at the same 94% during commit phase after restart.
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No third-party AV interference; plenty of disk space (>20GB free on C:).
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MSU is downloaded from official Microsoft Catalog; not corrupted (verified hash).
And the strange thing is that sporadically the update passes or get installed, But majority of the time its getting reverted back.
Note that the system was not patched from a very long time, and I have tried to install some old patches as well but there also it was causing the same issue.
What could be causing this failure specifically at 94% (likely during file/registry commit)? Are there hidden logs I can check (e.g., archived CBS .cab files)? Any known bugs in Servicing Stack or WinSxS that match this?
