Status of this walkthrough: This records a real full installation attempt using WinPOPBit (formerly POP4.2) and Windows 11 26H2 build
26300.9550on an AMD Phenom II system. WinPOPBit is experimental. Windows 11 on unsupported hardware is not supported by Microsoft. Back up all important data and prepare recovery media before starting.
In-place upgrades from the existing Windows 11 23H2 system were attempted with 24H2, 25H2 and 26H2 media. These attempts did not succeed, including attempts using Rufus-created media. Invoking Setup through setupprep.exe with /Product Server, including an attempt with /MigrateDrivers None, failed in the SafeOS/boot transition with:
0xC1900101-0x20017
The procedure below reflects this test machine:
22631.26300.9550.Other CPU families, firmware modes, image builds, and editions have not been established by this test. The process may differ for UEFI systems or other releases.
26300.9550.See the WinPOPBit README for current project prerequisites and changes. Use the revision being tested or documented rather than assuming every future version behaves identically.
Obtain the latest WinPOPBit source. To reproduce the source revision used in this test, check out:
git clone https://github.com/Smu1zel/WinPOPBit.git
Install the Python dependency in an elevated or appropriately configured Python environment:
py -m pip install pefile
The script may request Administrator elevation for Windows image mounting and offline registry/BCD work. The project README also documents its Windows ADK oscdimg.exe prerequisite; the builder can download it if needed.
Extract these files from a Windows 11 23H2 x64 image into the repository's blobs directory. Use the correct 64-bit or 32-bit source for each path:
| Source path inside the mounted 23H2 Windows image | Destination under WinPOPBit\blobs |
|---|---|
Windows\System32\WindowsCodecs.dll |
WindowsCodecs.dll |
Windows\System32\msxml6.dll |
msxml6.dll |
Windows\SysWOW64\msxml6.dll |
msxml6_wow64.dll |
Do not substitute the target 26H2 versions. WinPOPBit documents these 23H2 replacements as important workarounds for SSE4.1 instructions in WindowsCodecs.dll and msxml6.dll; omitting them can make Setup or post-install registration fail.
Here is an example Powersheel script you can customise to copy the above .dll files. Don't assume everything matches on your system, double check and adjust paths, filenames and indexes.
$Iso = 'C:\POP42\Win11_23H2_English_x64.iso'
Mount-DiskImage -ImagePath $Iso
$Drive = (Get-DiskImage -ImagePath $Iso | Get-Disk | Get-Partition | Get-Volume).DriveLetter
$Wim = "${Drive}:\sources\install.wim"
DISM /Get-WimInfo /WimFile:$Wim
New-Item -ItemType Directory -Force 'C:\POP42\Mount23H2' | Out-Null
DISM /Mount-Image /ImageFile:$Wim /Index:1 /MountDir:'C:\POP42\Mount23H2' /ReadOnly
New-Item -ItemType Directory -Force 'C:\POP42\blobs' | Out-Null
Copy-Item 'C:\POP42\Mount23H2\Windows\System32\WindowsCodecs.dll' 'C:\POP42\blobs\WindowsCodecs.dll' -Force
Copy-Item 'C:\POP42\Mount23H2\Windows\System32\msxml6.dll' 'C:\POP42\blobs\msxml6.dll' -Force
Copy-Item 'C:\POP42\Mount23H2\Windows\SysWOW64\msxml6.dll' 'C:\POP42\blobs\msxml6_wow64.dll' -Force
DISM /Unmount-Image /MountDir:'C:\POP42\Mount23H2' /Discard
Dismount-DiskImage -ImagePath $Iso
Review badblobs.xml before building. The test used these actions:
winload entries enabled, with patch_ci_filter=true and patch_boot_options=true:
Windows\System32\boot\winload.efiWindows\System32\winload.efiWindows\System32\winload.exe (the legacy-BIOS loader used by the test machine)The source ISO of Windows 11 26H2 used in the test was named:
26300.9550.260920-2000.26H2_GE_RELEASE_SVC_PROD3_CLIENTPRO_OEMRET_X64FRE_EN-US.ISO
The exact build command used was:
python winpopbit.py build -i "C:\POP42\26300.9550.260920-2000.26H2_GE_RELEASE_SVC_PROD3_CLIENTPRO_OEMRET_X64FRE_EN-US.ISO" -o "C:\POP42\Win11_26H2_POP42_WinloadPatched.iso" --index 1
Adjust paths and the image index for your own files. The test image's index 1 was Windows 11 Pro. Check the source ISO's indexes before building; do not assume index 1 is Pro in every ISO.
The output ISO was then used as the source for the Rufus USB. Keep the original unmodified ISO and the patched ISO separate so it is clear which image was written to the USB.
Win11_26H2_POP42_WinloadPatched.iso.
With the USB booted, press F8 to open the Advanced Boot Options and choose Disable Driver Signature Enforcement. Menu wording and key behaviour may depend on boot stage Windows version.
When the process offers the new white Setup UI look for a link in bottom left of the screen called Previous Version Setup and click it.
Proceed with a Full clean installation, not an in-place upgrade. Choose the target disk and partitions carefully.
If you don't pick Previous Version Setup the newer white Setup UI blocks installation at the SSE4.2 CPU check, while the previous method allows the installation to proceed.
The first restart after image application displayed a signature-verification error for the modified kernel (\Windows\System32\ntoskrnl.exe, error 0xc0000428.
Press F9 to choose another operating-system entry. The menu showed two entries named Windows 11, both associated with Volume 3. Selecting the top entry failed to boot. Selecting the bottom entry continued Setup; it displayed the Windows logo and spinning dots, then proceeded through another automatic reboot to “Just a moment” without requiring further input.
This is an observation from one machine, not a general rule. Do not blindly select the bottom entry on every computer: menu order, volume numbering and BCD entries can differ. The important result to verify is that Setup continues rather than returning to the old OS or entering recovery.
Let Setup continue. Do not interrupt it just because disk activity is heavy or because it restarts more than once.
winver
Do not install cumulative updates until the initial system is verified and backed up. Modified protected binaries may be replaced by servicing, and this is an unsupported configuration.
Use Group Policy to configure Windows Updates to only notify of updates but not update as that could make your machine fail to boot after an update. Review update notes to check if update is updating any of the modified boot files or the three .dll files. Where those are updated you can explore creating an ISO with UUP that contains the update but note that this is not guaranteed to work.