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

    Fault : DFSR event 4012 -- replication stopped after exceeding MaxOfflineTimeInDays
    Fix   : Rebuild SYSVOL replication with an authoritative restore
    Source: https://jbtecwiz.com/support/srv-dfsr-4012

    Run as     : Elevated PowerShell on all DCs
    Expect     : 1-2 hours
    Risk       : high
    Reversible : NO -- read the undo note below before running

    WHEN THIS IS THE RIGHT FIX
    SYSVOL is the affected folder. Pick the DC with the SYSVOL contents you
    trust as authoritative -- usually the PDC emulator.

    HOW TO UNDO IT
    Restore SYSVOL from the backup taken in step 2. There is no in-place
    undo once the authoritative sync has run.

    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 '  DFSR event 4012 -- replication stopped after exceeding MaxOfflineTimeInDays' -ForegroundColor White
Write-Host '  Rebuild SYSVOL replication with an authoritative restore' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: high   NOT REVERSIBLE   1-2 hours' -ForegroundColor Yellow
Write-Host ''
Show-Prose 'Undo: Restore SYSVOL from the backup taken in step 2. There is no in-place undo once the authoritative sync has run.' 'Yellow'
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 'Identify the PDC emulator and confirm its SYSVOL contents are correct.' -Command {
    Get-ADDomain | Select-Object PDCEmulator
}

Invoke-Step -Number 2 -Do 'Back up the SYSVOL folder on every DC before touching anything.' -Why 'This procedure overwrites SYSVOL on every non-authoritative DC from the authoritative one. If the wrong DC is chosen, every DC ends up with the wrong policies.' -Command {
    robocopy C:\Windows\SYSVOL_DFSR D:\sysvol-backup /E
}

Invoke-Step -Number 3 -Do 'Stop the DFS Replication service on all DCs.' -Command {
    Stop-Service DFSR
}

Invoke-Step -Number 4 -Do 'On the authoritative DC, set msDFSR-Options to 1 on its SYSVOL Subscription object, and set msDFSR-Enabled to FALSE on all DCs'' subscriptions.' -Manual

Invoke-Step -Number 5 -Do 'Start DFSR on the authoritative DC, wait for event 4602, then set msDFSR-Enabled back to TRUE on the others and start their DFSR services.' -Manual

Invoke-Step -Number 6 -Do 'Force AD replication so the flags propagate.' -Command {
    repadmin /syncall /AdeP
}

Write-Rule "  Confirm it worked"
Show-Prose 'Event 4602 appears on each DC and SYSVOL contents match everywhere.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-WinEvent -LogName 'DFS Replication' -MaxEvents 10 | Where-Object Id -eq 4602
}

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/srv-dfsr-4012' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Restore SYSVOL from the backup taken in step 2. There is no in-place undo once the authoritative sync has run.' 'DarkGray'
Write-Rule