#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : 0xC000021A -- STATUS_SYSTEM_PROCESS_TERMINATED
    Fix   : Clear the stuck pending update from WinRE
    Source: https://jbtecwiz.com/support/win-0xc000021a

    Run as     : Windows Recovery Environment
    Expect     : 30 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    It started after an update. A half-applied transaction is the most
    common cause of this bugcheck.

    HOW TO UNDO IT
    Rename pending.old back to pending.xml from WinRE if the revert made
    things worse.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 6"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  0xC000021A -- STATUS_SYSTEM_PROCESS_TERMINATED' -ForegroundColor White
Write-Host '  Clear the stuck pending update from WinRE' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   30 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'Boot to WinRE and open Troubleshoot -> Advanced options -> Command Prompt.' -Manual

Invoke-Step -Number 2 -Do 'Find the Windows volume -- it is usually D: inside WinRE, not C:.' -Command {
    cmd.exe /c 'diskpart & list volume & exit'
}

Invoke-Step -Number 3 -Do 'Look at what is pending.' -Command {
    cmd.exe /c 'DISM /Image:D:\ /Get-Packages /Format:Table | findstr /i "Install Pending"'
}

Invoke-Step -Number 4 -Do 'Revert the pending actions.' -Why 'This rolls the interrupted transaction back to the last consistent state, which is exactly what the machine failed to do on its own.' -Command {
    cmd.exe /c 'DISM /Image:D:\ /Cleanup-Image /RevertPendingActions'
}

Invoke-Step -Number 5 -Do 'Rename the pending operations file so the servicing stack does not retry the same thing on boot.' -Command {
    cmd.exe /c 'ren D:\Windows\WinSxS\pending.xml pending.old'
}

Invoke-Step -Number 6 -Do 'Exit and restart. Expect the first boot to be slow.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'Windows reaches the sign-in screen. Check the servicing state once in.' 'White'
Write-Host ''
if (-not $DryRun) {
    DISM /Online /Cleanup-Image /ScanHealth
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/win-0xc000021a' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Rename pending.old back to pending.xml from WinRE if the revert made things worse.' 'DarkGray'
Write-Rule