Update Boot Code failure when trying to reinstall W10

Question

I am trying to reinstall Windows 10 (in order to be able to install Windows 11). I consistently get "Windows 10 installation failed" messages near the end of the process. W10 is working just fine otherwise.

My self-assembled machine had a previous windows installation on a hard drive which is no longer connected; the error messages I get suggest that the installer is still seeing two boot records (the current one and the old one) and can't decide which one to execute.

This is the output of SetupDiag.exe:

QUOTE

<SetupDiag xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="https://docs.microsoft.com/en-us/windows/deployment/upgrade/setupdiag">

<Version>1.6.0.0</Version>

<ProfileName>FindAbruptDownlevelFailure</ProfileName>

<ProfileGuid>55882B1A-DA3E-408A-9076-23B22A0472BD</ProfileGuid>

 

<LogErrorLine>2025-09-19 13:22:12, Error SP Operation failed: Update Boot Code. Error: 0x80004005[gle=0x000000b7]</LogErrorLine>

 

<FailureData>Error: SetupDiag reports abrupt down-level failure.Last Operation: FinalizeError: 0x80004005 - 0x50016</FailureData>

 

<FailureData>LogEntry: 2025-09-19 13:22:12, Error SP Operation failed: Update Boot Code. Error: 0x80004005[gle=0x000000b7]</FailureData>

 

<FailureData>Refer to "https://docs.microsoft.com/en-us/windows/desktop/Debug/system-error-codes" for error information.</FailureData>

 

<FailureDetails>ErrorCode = 0x80004005, ExCode = 0x50016, Oper = Finalize</FailureDetails>

 

<SetupPhaseInfo>

<PhaseName>Finalize</PhaseName>

<PhaseStartTime>9/19/2025 1:22:09 PM</PhaseStartTime>

<PhaseEndTime>1/1/0001 12:00:00 AM</PhaseEndTime>

<PhaseTimeDelta>0:00:00:00.0000000</PhaseTimeDelta>

<CompletedSuccessfully>false</CompletedSuccessfully>

</SetupPhaseInfo>

<SetupOperationInfo>

<OperationName>Update Boot Code</OperationName>

<OperationStartTime>9/19/2025 1:22:12 PM</OperationStartTime>

<OperationEndTime>1/1/0001 12:00:00 AM</OperationEndTime>

<OperationTimeDelta>0:00:00:00.0000000</OperationTimeDelta>

<CompletedSuccessfully>false</CompletedSuccessfully>

</SetupOperationInfo>

</SetupDiag>

UNQUOTE

I don't want to poke around in the register unless I'm certain what I want to change. Can anyone suggest how to find and delete the reference to the old boot record? (I have tried all the usual fixes. The SSD has no flaws per HDTunePro.) Thanks for any help you can give me.

Answer 1

Glad it's sorted.

Can anyone suggest how to find and delete the reference to the old boot record?

Sort of, yes. You were right. Deleting and rebuilding the EFI partition was the ticket.

---

I'm a volunteer here. So, I don't have a boss. :-) But I guess CET might go through some of the user feedback.

Answer 2

1] Please open Disk Management and maximize it. Adjust the column widths in the top pane to make all the entries visible. Post a screenshot.

2] Launch msinfo32.exe, and click System Summary. Resize the columns in the right pane to make the entries visible, and post a screenshot.

3] Open the admin Command Prompt and run:

bcdedit
diskpart
list disk
select disk 0
list part
list vol
exit
reagentc /info

Post the output.

Answer 3

After creating the USB setup disk, boot the subject computer using it. To do so, you may need to change the boot order in the BIOS/UEFI settings. Consult your system or motherboard manual to learn how to access the UEFI settings for your model.

On the Windows Setup language selection screen, press Shift + F10 to enter Windows RE Command Prompt.

In the WinRE Command Prompt, type the following commands:

diskpart

select disk 0

list part

select part 1

assign letter=Y

list vol

exit

Take photos of the output screen using your phone and share the images here. Don't quit WinRE yet. A few more commands need to be run.

Answer 4

Answer 5

Ok.

Assuming you haven't closed the WinRE screen, please run these commands now.

xcopy /h Y:\EFI\Microsoft\Boot\BCD C:\

format Y: /fs:FAT32 /q

Note: When you run the format command, you'll be prompted to type the volume label. Type EFI and press Enter.

Once done, run the final command.

bcdboot  C:\Windows /s Y: /f UEFI

Post the screenshot(s).