DNS problems

Because both built-in repair and the USB in-place installation failed, diagnose the Setup failure with SetupDiag before attempting one more in-place repair that preserves files, applications, and settings.

1. Back up before further repair attempts

Copy irreplaceable files to external storage, export any game saves not synchronized to the cloud, and record the BitLocker recovery key if device encryption is enabled. Confirm that Settings > System > Activation shows Windows activated.

Also ensure the Windows drive has sufficient free space for Setup. Microsoft recommends backing up before reinstalling and confirms that the reinstalled edition must match the existing license—Windows 11 Pro in this case.^1^

2. Identify why the previous in-place installation failed

Windows Setup normally runs SetupDiag automatically. First open:

C:\Windows\Logs\SetupDiag\SetupDiagResults.xml

If that file is absent or inconclusive, download the latest SetupDiag using another device if necessary, copy it to the affected PC, and run this from Command Prompt (Admin):

mkdir C:\SetupDiag
SetupDiag.exe /Output:C:\SetupDiag\Results.log
notepad C:\SetupDiag\Results.log

SetupDiag parses the failed-upgrade logs and reports matched failure details; if it reports multiple failures, the last failure is normally the fatal one.^2^

If SetupDiag produces only a generic or unmatched result, preserve these files before another attempt:

C:\$WINDOWS.~BT\Sources\Panther\setupact.log
C:\$WINDOWS.~BT\Sources\Panther\setuperr.log
C:\Windows\Logs\SetupDiag\SetupDiagResults.xml
C:\Windows\Logs\CBS\CBS.log

Setupact.log is the primary detailed Setup log, while setuperr.log contains the high-level errors.^3^ Post the SetupDiag result and final section of setuperr.log; do not repeatedly rerun Setup without identifying the rollback reason.

3. Retry the in-place repair only after addressing the reported blocker

Use current Windows 11 media matching:

• Edition: Windows 11 Pro
• Language: the installed Windows display/base language
• Architecture: x64, assuming the present installation is x64
• Release: a supported same-or-newer Windows release

Start setup.exe from inside the running Windows desktop, not by booting from the USB. Select:

1. Change what to keep
2. Keep personal files and apps
3. Install

That selection preserves personal files, applications, and settings.^1^

Cancel Setup if “Keep personal files and apps” is unavailable. Continuing with another selection would remove applications or data.

Apply these measures only when the SetupDiag result supports them:

• Driver/0xC1900101 failure: disconnect nonessential peripherals and update or remove the named driver.
• Background-process error such as 0x8007042B-0x4000D: retry in a clean boot. Afterward, open msconfig, select Normal startup, and restart.^4^
• Third-party antivirus specifically implicated: temporarily disable or uninstall it. This reduces protection; verify Microsoft Defender becomes active, avoid untrusted networks, and reinstall or re-enable the security product immediately after the attempt.

Do not repeat the local-WIM DISM command unless a properly serviced source becomes available. For DISM specifically, a source below the target’s patch level can lack files required by the installed system.^5^

4. Restore DNS while investigating Setup

The DNS failure may be separately recoverable. Run these commands from Command Prompt (Admin), then restart:

netsh winsock reset
netsh int ip reset
ipconfig /release
ipconfig /renew
ipconfig /flushdns

These reset Winsock and TCP/IP, renew the address, and clear the DNS resolver cache.^6^

If DNS still fails, use Settings > Network & internet > Advanced network settings > Network reset > Reset now. This removes and reinstalls network adapters and resets their settings; VPN clients and Hyper-V virtual switches may require reconfiguration afterward.^6^

If the preservation repair still cannot complete

• Reset this PC > Keep my files preserves personal files but removes installed applications and settings.^7^
• A clean installation removes personal files, applications, OEM customizations, and settings. It is the final option if SetupDiag does not reveal a correctable blocker or the corrected in-place repair fails again.^1^

Therefore, preserving everything is still possible only if the in-place repair can be made to complete; Reset or clean installation cannot preserve all installed applications and settings.

References

1. Reinstall Windows with the installation media
2. SetupDiag
3. Deployment Troubleshooting and Log Files
4. [Windows 11](https://support.microsoft.com/windows/deployment/install-upgrade/get-help-with-windows-upgrade-and-installation-errors)
5. Configure a Windows Repair Source
6. [Windows 11](https://support.microsoft.com/windows/experience/connectivity-networking/fix-ethernet-connection-problems-in-windows#on-your-pc)
7. [Windows 11](https://support.microsoft.com/windows/experience/backup-recovery/reset-your-pc#summary)