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

    Fault : 0x8024402C / 0x80244022 -- the client cannot talk to WSUS
    Fix   : Recover the WSUS application pool
    Source: https://jbtecwiz.com/support/win-wu-8024402c

    Run as     : Elevated PowerShell on the WSUS server
    Expect     : 20 minutes
    Risk       : low
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    Every client fails at once. WsusPool stopping under memory pressure is
    the classic cause and it recurs until the limit is raised.

    HOW TO UNDO IT
    Set privateMemory back to 1843200 if the server has genuine memory
    pressure that needs bounding.

    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 5"
    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 '  0x8024402C / 0x80244022 -- the client cannot talk to WSUS' -ForegroundColor White
Write-Host '  Recover the WSUS application pool' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: low   Reversible   20 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 'Check whether the pool is running.' -Command {
    Import-Module WebAdministration
    Get-ChildItem IIS:\AppPools | Select-Object Name, State
}

Invoke-Step -Number 2 -Do 'Start it if it has stopped.' -Command {
    Start-WebAppPool -Name WsusPool
}

Invoke-Step -Number 3 -Do 'Raise the private memory limit -- the 1.8 GB default is far too low for a WSUS of any size. 0 means unlimited.' -Why 'When the pool exceeds the limit IIS stops it, and every client immediately starts failing with connection errors that look like a client-side problem.' -Command {
    Set-ItemProperty 'IIS:\AppPools\WsusPool' -Name recycling.periodicRestart.privateMemory -Value 0
}

Invoke-Step -Number 4 -Do 'Turn off the queue-length based rapid-fail protection that compounds the outage.' -Command {
    Set-ItemProperty 'IIS:\AppPools\WsusPool' -Name failure.rapidFailProtection -Value $false
}

Invoke-Step -Number 5 -Do 'Run the WSUS server cleanup wizard, and if the database has never been maintained, apply the standard WSUS index maintenance script.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'The pool stays started and clients scan successfully.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-ChildItem IIS:\AppPools | Select-Object Name, State
}

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-wu-8024402c' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Set privateMemory back to 1843200 if the server has genuine memory pressure that needs bounding.' 'DarkGray'
Write-Rule