Windows 11 KB5094126 keeps failing

[RZman]

It found bootstat folder

 

[ChatGPT]

Ron, the bootstat folder is not the one we need.
bootstat is just Windows boot-status tracking. It will not tell us why the repair/update failed with:
0xC1900101
So don’t worry about that folder.

Let’s check whether the rollback logs still exist​

Please run this in PowerShell as Administrator:
Test-Path 'C:\$Windows.~BT'
Then run:
Get-ChildItem 'C:\$Windows.~BT\Sources' -Force | Select-Object Name,Mode,LastWriteTime
Post what it shows.

What we are looking for​

We need to know whether these folders still exist:

C:\$Windows.~BT\Sources\Rollback
C:\$Windows.~BT\Sources\Panther

If they are gone, Windows probably cleaned up the repair-install logs after rolling back.

If the folders are missing​

Then we will stop chasing rollback files and use Event Viewer logs instead.
Run this in PowerShell as Administrator:
Get-WinEvent -FilterHashtable @{LogName='System'; Id=1001,41,6008} -MaxEvents 20 | Format-List TimeCreated,Id,ProviderName,Message
Copy/paste the output here.

Also export setup/update logs to Downloads​

Run these two commands:
wevtutil epl Setup "$env:USERPROFILE\Downloads\Setup.evtx"
Then:
wevtutil epl Microsoft-Windows-WindowsUpdateClient/Operational "$env:USERPROFILE\Downloads\WindowsUpdateClient.evtx"
That should create two files in Downloads:

Setup.evtx
WindowsUpdateClient.evtx

You can upload those here if the forum allows it.

Bottom line​

The bootstat folder is not useful for this issue. We need either:

C:\$Windows.~BT\Sources\Rollback
C:\$Windows.~BT\Sources\Panther

or the exported Event Viewer logs.
And still: do not click Retry yet. The 0xC1900101 failure plus the PAGE_FAULT_IN_NONPAGED_AREA blue screen still points toward a driver/setup rollback problem.

 

[RZman]

 

[RZman]

Are any of these useful

 

[ChatGPT]

Ron, perfect — that is the folder we needed. You found the rollback log folder.
The important thing: do not zip that whole folder. Your setupact.log alone is about:
372,410 KB
That is why PowerShell ran out of memory when trying to compress everything.

What we need from this folder​

The most useful files in your screenshot are:

setuperr.log
SetupPlatform.Drivers.ini
SetupPlatform.ini
rollbackinfo.ini
diagerr.xml
diagwrn.xml
WinSetupMon.log
FolderMoveLog.TXT

And we need a small extract from the huge:
setupact.log

Run this PowerShell command​

Open PowerShell as Administrator and paste this whole block:

$src='C:\$Windows.~BT\Sources\Rollback'
$dest="$env:USERPROFILE\Downloads\WU-Rollback-Small"

New-Item -ItemType Directory -Force $dest | Out-Null

Copy-Item "$src\setuperr.log" $dest -Force -ErrorAction SilentlyContinue
Copy-Item "$src\SetupPlatform.Drivers.ini" $dest -Force -ErrorAction SilentlyContinue
Copy-Item "$src\SetupPlatform.ini" $dest -Force -ErrorAction SilentlyContinue
Copy-Item "$src\rollbackinfo.ini" $dest -Force -ErrorAction SilentlyContinue
Copy-Item "$src\diagerr.xml" $dest -Force -ErrorAction SilentlyContinue
Copy-Item "$src\diagwrn.xml" $dest -Force -ErrorAction SilentlyContinue
Copy-Item "$src\WinSetupMon.log" $dest -Force -ErrorAction SilentlyContinue
Copy-Item "$src\FolderMoveLog.TXT" $dest -Force -ErrorAction SilentlyContinue

Get-Content "$src\setupact.log" -Tail 3000 | Out-File "$dest\setupact_tail_3000.txt" -Encoding utf8

Select-String -Path "$src\setupact.log" -Pattern "error","fail","rollback","bugcheck","0xC1900101","0x50","driver","PAGE_FAULT" -CaseSensitive:$false | Select-Object -Last 500 | Out-File "$dest\setupact_errors_extract.txt" -Encoding utf8

Compress-Archive -Path "$dest\*" -DestinationPath "$env:USERPROFILE\Downloads\WU-Rollback-Small.zip" -Force

Then upload this file​

Upload:
C:\Users\Ron\Downloads\WU-Rollback-Small.zip

Why we are doing it this way​

Your folder contains the exact logs from the failed repair attempt. Since the repair failed with:
0xC1900101
and you had a blue screen:
PAGE_FAULT_IN_NONPAGED_AREA 0x50
we are looking for the driver or setup phase that caused the rollback.

Do not click Retry yet​

For now, still avoid:

Retry
Retry all
Fix problems using Windows Update
KB5094126 manual install

Once we see that small zip, we should have a much better chance of identifying the actual culprit.

 

[ChatGPT]

[ChatGPT at 2026-06-25 16:34 UTC]: Yes, Ron — several of those are useful.
The most useful ones are:

setuperr.log
diagerr.xml
diagwrn.xml
rollbackinfo.ini
SetupPlatform.Drivers.ini
SetupPlatform.ini
WinSetupMon.log
MigLog.xml
LogRestore.TXT
FolderMoveLog.TXT

Do not upload setupact.log yet.
That one is huge in your screenshot — about 372 MB — and that is what likely caused the PowerShell zip error.

Best next step​

Let’s package only the useful smaller files.
Open PowerShell as Administrator and run this:

$src='C:\$Windows.~BT\Sources\Rollback'
$dest="$env:USERPROFILE\Downloads\WU-Rollback-Small"

New-Item -ItemType Directory -Force $dest | Out-Null

$files = @(
'setuperr.log',
'diagerr.xml',
'diagwrn.xml',
'rollbackinfo.ini',
'rollbackstate.dat',
'SetupPlatform.ini',
'SetupPlatform.Drivers.ini',
'WinSetupMon.log',
'MigLog.xml',
'LogRestore.TXT',
'FolderMoveLog.TXT'
)

foreach ($f in $files) {
    Copy-Item (Join-Path $src $f) $dest -Force -ErrorAction SilentlyContinue
}

Compress-Archive -Path "$dest\*" -DestinationPath "$env:USERPROFILE\Downloads\WU-Rollback-Small.zip" -Force

Then upload this file:
C:\Users\Ron\Downloads\WU-Rollback-Small.zip

If the zip fails again​

If it still gives an error, just upload these individually first:

setuperr.log
diagerr.xml
diagwrn.xml
rollbackinfo.ini
SetupPlatform.Drivers.ini
SetupPlatform.ini

Those are small and likely enough to identify the rollback cause.

Most important file​

Start with this one if you only upload one:
setuperr.log
That file is small and usually contains the actual setup failure line.

Leave this one alone for now​

setupact.log
It may be useful later, but it is too large to handle right now.
You found the right folder. Now we just need the small logs from it.

 

[RZman]

Copyright (C) Microsoft Corporation. All rights reserved.

Install the latest PowerShell for new features and improvements! Windows PowerShell update message FAQ - PowerShell | Microsoft Learn

PS C:\WINDOWS\system32> New-Item -ItemType Directory -Force "$env:USERPROFILE\Desktop\RollbackLogsSmall"


Directory: C:\Users\Ron\Desktop


Mode LastWriteTime Length Name
---- ------------- ------ ----
d----- 06/25/2026 10:18 RollbackLogsSmall


PS C:\WINDOWS\system32> Copy-Item "$env:USERPROFILE\Desktop\RollbackLogs\*.log" "$env:USERPROFILE\Desktop\RollbackLogsSmall" -Force -ErrorAction SilentlyContinue
>> Copy-Item "$env:USERPROFILE\Desktop\RollbackLogs\*.xml" "$env:USERPROFILE\Desktop\RollbackLogsSmall" -Force -ErrorAction SilentlyContinue
>> Copy-Item "$env:USERPROFILE\Desktop\RollbackLogs\*.txt" "$env:USERPROFILE\Desktop\RollbackLogsSmall" -Force -ErrorAction SilentlyContinue
PS C:\WINDOWS\system32> Code:
>> $src='C:\$Windows.~BT\Sources\Rollback'
>> $dest="$env:USERPROFILE\Downloads\WU-Rollback-Small"
>>
>> New-Item -ItemType Directory -Force $dest | Out-Null
>>
>> $files = @( >> 'setuperr.log', >> 'diagerr.xml', >> 'diagwrn.xml', >> 'rollbackinfo.ini', >> 'rollbackstate.dat',
>> 'SetupPlatform.ini',
>> 'SetupPlatform.Drivers.ini',
>> 'WinSetupMon.log',
>> 'MigLog.xml',
>> 'LogRestore.TXT',
>> 'FolderMoveLog.TXT'
>> )
>>
>> foreach ($f in $files) {
>> Copy-Item (Join-Path $src $f) $dest -Force -ErrorAction SilentlyContinue
>> }
>>
>> Compress-Archive -Path "$dest\*" -DestinationPath "$env:USERPROFILE\Downloads\WU-Rollback-Small.zip" -Force
Code: : The term 'Code:' is not recognized as the name of a cmdlet, function, script file, or operable program. Check
the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:1
+ Code:
+ ~~~~~
+ CategoryInfo : ObjectNotFound: (Code::String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundExceptio

 

[ChatGPT]

Ron, that error is harmless. PowerShell only complained because you accidentally pasted the label:
Code:
PowerShell tried to run Code: as a command, and of course it does not exist.
The important part is that the rest of the commands likely still ran after that.

Check if the zip was created​

Press Windows + R, paste this, and press Enter:
%USERPROFILE%\Downloads
Look for:
WU-Rollback-Small.zip
If you see it, upload that file here.

If you do not see the zip​

Run this in PowerShell:
dir "$env:USERPROFILE\Downloads" | findstr WU-Rollback
If it shows:

WU-Rollback-Small
WU-Rollback-Small.zip

then the zip exists in Downloads.

If the zip still does not exist​

Run this clean version again, but do not include Code::

$src='C:\$Windows.~BT\Sources\Rollback'
$dest="$env:USERPROFILE\Downloads\WU-Rollback-Small"

New-Item -ItemType Directory -Force $dest | Out-Null

$files = @(
'setuperr.log',
'diagerr.xml',
'diagwrn.xml',
'rollbackinfo.ini',
'rollbackstate.dat',
'SetupPlatform.ini',
'SetupPlatform.Drivers.ini',
'WinSetupMon.log',
'MigLog.xml',
'LogRestore.TXT',
'FolderMoveLog.TXT'
)

foreach ($f in $files) {
    Copy-Item (Join-Path $src $f) $dest -Force -ErrorAction SilentlyContinue
}

Compress-Archive -Path "$dest\*" -DestinationPath "$env:USERPROFILE\Downloads\WU-Rollback-Small.zip" -Force

Then check Downloads again for:
WU-Rollback-Small.zip

If uploading the zip is annoying​

You can upload just this one file first:
C:\$Windows.~BT\Sources\Rollback\setuperr.log
That is the most important small log. It may tell us exactly why the repair failed with:
0xC1900101

 

[RZman]

Here is the file

 

[RZman]

the rollback is just above

 

[ChatGPT]

Ron, I don’t actually see the rollback zip/log attachment in this post. I can see from the thread that you were trying to create/upload the rollback package, and that the important files were the small rollback logs rather than the huge setupact.log . But I do not have the contents of the rollback log to read yet.

What to send now​

Please upload one of these:
C:\Users\Ron\Downloads\WU-Rollback-Small.zip
or, if that zip does not exist, upload this file directly:
C:\$Windows.~BT\Sources\Rollback\setuperr.log
That is the most important one.

If uploading is still giving trouble​

Do this instead:

1. Open File Explorer.
2. Go to:

C:\$Windows.~BT\Sources\Rollback

1. Right-click this file:

setuperr.log

1. Choose Open with > Notepad.
2. Press Ctrl + A.
3. Press Ctrl + C.
4. Paste the contents here.

If it is too long, paste only the last 50–100 lines.

About the CRT warning​

If you are getting the CRT warning again, please post the exact wording or a screenshot of that warning. That may matter, especially because your repair install failed with:
0xC1900101
and you also saw:

PAGE_FAULT_IN_NONPAGED_AREA
0x50

Those point more toward a driver/setup rollback issue than normal Windows file corruption. Your SFC, DISM, and CHKDSK results were clean, so the rollback log is the next important clue.

For now​

Do not click Retry yet.
Wait until we see setuperr.log or the small rollback zip.