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

    Fault : SYSVOL not shared, or Group Policy files missing on one controller
    Fix   : Resynchronise the affected controller from a healthy one
    Source: https://jbtecwiz.com/support/srv-id-sysvol

    Run as     : Elevated PowerShell on the broken controller
    Expect     : 60 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    One controller is affected and at least one is healthy.

    HOW TO UNDO IT
    The controller pulls from its partners; nothing local is authoritative
    during this.

    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 '  SYSVOL not shared, or Group Policy files missing on one controller' -ForegroundColor White
Write-Host '  Resynchronise the affected controller from a healthy one' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   60 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 'Confirm the state.' -Command {
    dcdiag /test:sysvolcheck /test:netlogons /v | Select-String 'passed|failed'
    net share
    Get-WinEvent -LogName 'DFS Replication' -MaxEvents 40 | Format-Table TimeCreated,Id,Message -Wrap
}

Invoke-Step -Number 2 -Do 'Check the replication state of the SYSVOL group.' -Why 'State 4 is normal. State 5 means it is in an error state, and state 2 means initial synchronisation. Anything other than 4 explains the missing share without further investigation.' -Command {
    Get-CimInstance -Namespace root\microsoftdfs -ClassName DfsrReplicatedFolderInfo | Format-Table ReplicatedFolderName,State
}

Invoke-Step -Number 3 -Do 'Set this controller to non-authoritative, so it pulls a fresh copy from a healthy partner.' -Command {
    $dn = (Get-ADDomainController -Identity $env:COMPUTERNAME).ComputerObjectDN
    Set-ADObject -Identity "CN=SYSVOL Subscription,CN=Domain System Volume,CN=DFSR-LocalSettings,$dn" -Replace @{ 'msDFSR-Enabled' = $false }
    repadmin /syncall /AdeP
    Restart-Service DFSR
}

Invoke-Step -Number 4 -Do 'Wait for event 4114, then re-enable.' -Command {
    Get-WinEvent -LogName 'DFS Replication' -MaxEvents 10 | Where-Object Id -eq 4114 | Format-List TimeCreated,Message
}

Invoke-Step -Number 5 -Do 'Re-enable replication and let it pull.' -Command {
    $dn = (Get-ADDomainController -Identity $env:COMPUTERNAME).ComputerObjectDN
    Set-ADObject -Identity "CN=SYSVOL Subscription,CN=Domain System Volume,CN=DFSR-LocalSettings,$dn" -Replace @{ 'msDFSR-Enabled' = $true }
    repadmin /syncall /AdeP
    Restart-Service DFSR
}

Invoke-Step -Number 6 -Do 'Wait for event 4614 followed by 4604, which is the confirmation that SYSVOL is now shared.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'SYSVOL and NETLOGON are shared and dcdiag passes both tests.' 'White'
Write-Host ''
if (-not $DryRun) {
    net share | findstr /i "sysvol netlogon"
    dcdiag /test:sysvolcheck /test:netlogons | Select-String 'passed|failed'
}

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-id-sysvol' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: The controller pulls from its partners; nothing local is authoritative during this.' 'DarkGray'
Write-Rule