Plan and Execute Windows Server Upgrades Using Supported Paths

Before starting any upgrade, document your current system thoroughly. This creates a baseline and helps troubleshoot issues later.

Open PowerShell as Administrator and run these commands to capture system information:

Get-ComputerInfo -Property WindowsBuildLabEx,WindowsEditionID,TotalPhysicalMemory | Out-File -FilePath C:\Temp\computerinfo.txt
systeminfo.exe | Out-File -FilePath C:\Temp\systeminfo.txt
ipconfig /all | Out-File -FilePath C:\Temp\ipconfig.txt
Get-WindowsFeature | Where-Object InstallState -eq "Installed" | Out-File -FilePath C:\Temp\installed-features.txt

Document your current Windows Server version and edition:

$OS = Get-WmiObject -Class Win32_OperatingSystem
Write-Host "Current Version: $($OS.Caption)"
Write-Host "Build Number: $($OS.BuildNumber)"
Write-Host "Edition: $($OS.OperatingSystemSKU)"

Copy these files to a USB drive or network location. This documentation will be crucial if you need to restore services or troubleshoot post-upgrade.

Not all Windows Server versions can upgrade directly to newer versions. Check the official upgrade matrix to determine your path.

Use this PowerShell command to identify your current version:

$Version = (Get-ItemProperty "HKLM:SOFTWARE\Microsoft\Windows NT\CurrentVersion").ReleaseId
$Build = (Get-ItemProperty "HKLM:SOFTWARE\Microsoft\Windows NT\CurrentVersion").CurrentBuild
Write-Host "Release ID: $Version, Build: $Build"

Based on Microsoft's 2026 supported upgrade paths:

System preparation is critical for upgrade success. Start by installing all available updates and creating comprehensive backups.

Install Windows Updates:

Install-Module PSWindowsUpdate -Force
Get-WUInstall -AcceptAll -AutoReboot

Create a system backup using Windows Server Backup:

Import-Module WindowsServerBackup
$Policy = New-WBPolicy
$VolumeBackupLocation = New-WBBackupTarget -VolumePath "E:"
Add-WBBackupTarget -Policy $Policy -Target $VolumeBackupLocation
$Volume = Get-WBVolume -VolumePath "C:"
Add-WBVolume -Policy $Policy -Volume $Volume
Start-WBBackup -Policy $Policy

Verify system requirements for the target version. For Windows Server 2025:

$RAM = [math]::Round((Get-CimInstance Win32_PhysicalMemory | Measure-Object -Property capacity -Sum).sum /1gb,2)
$Disk = Get-WmiObject -Class Win32_LogicalDisk -Filter "DriveType=3" | Select-Object Size,FreeSpace
Write-Host "RAM: $RAM GB (Minimum: 2GB for Desktop Experience)"
foreach($Drive in $Disk) {
    $FreeGB = [math]::Round($Drive.FreeSpace /1GB,2)
    Write-Host "Free Space: $FreeGB GB (Minimum: 32GB required)"
}

Download the Windows Server 2025 ISO from the Microsoft Volume Licensing Service Center or Evaluation Center. You'll need valid credentials and licensing.

Mount the ISO file and verify its contents:

$ISOPath = "C:\Downloads\WindowsServer2025.iso"
$MountResult = Mount-DiskImage -ImagePath $ISOPath -PassThru
$DriveLetter = ($MountResult | Get-Volume).DriveLetter
Write-Host "ISO mounted to drive: $DriveLetter"
Get-ChildItem "${DriveLetter}:\" | Select-Object Name,Length

Verify the setup.exe file exists and check the Windows Server edition available:

$SetupPath = "${DriveLetter}:\setup.exe"
if (Test-Path $SetupPath) {
    Write-Host "Setup.exe found at: $SetupPath"
    $FileVersion = (Get-ItemProperty $SetupPath).VersionInfo.FileVersion
    Write-Host "Setup version: $FileVersion"
} else {
    Write-Host "ERROR: Setup.exe not found!"
}

Check available editions in the ISO:

dism /Get-WimInfo /WimFile:"${DriveLetter}:\sources\install.wim"

Ensure the target edition matches your current installation (Standard to Standard, Datacenter to Datacenter). Mismatched editions will cause upgrade failures.

Now execute the actual upgrade process. This step requires careful monitoring and can take several hours depending on your system.

Navigate to the mounted ISO and launch setup with elevated privileges:

Start-Process -FilePath "${DriveLetter}:\setup.exe" -Verb RunAs

During the setup wizard:

1. Enter your product key when prompted
2. Select the same edition as your current installation
3. Choose "Keep personal files, apps, and Windows settings" for in-place upgrade
4. Select "Download and install updates (recommended)" for latest patches

Monitor the upgrade progress. The system will reboot multiple times. You can check progress after each reboot:

Get-ItemProperty "HKLM:SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\State" | Select-Object ImageState

If the ImageState shows "IMAGE_STATE_COMPLETE", the upgrade finished successfully.

Verification after upgrade completion:

$OS = Get-WmiObject -Class Win32_OperatingSystem
Write-Host "New Version: $($OS.Caption)"
Write-Host "Build Number: $($OS.BuildNumber)"
winver

After the upgrade completes, verify all services and roles are functioning correctly. This step is crucial to ensure business continuity.

Check all installed Windows features are still present:

Compare-Object (Get-Content C:\Temp\installed-features.txt) (Get-WindowsFeature | Where-Object InstallState -eq "Installed" | Select-Object -ExpandProperty Name)

Verify critical services are running:

$CriticalServices = @("Spooler", "DHCP", "DNS", "W32Time", "EventLog")
foreach ($Service in $CriticalServices) {
    $Status = Get-Service -Name $Service -ErrorAction SilentlyContinue
    if ($Status) {
        Write-Host "$Service`: $($Status.Status)"
    }
}

Test network connectivity and domain membership:

Test-ComputerSecureChannel -Verbose
nltest /dsgetdc:$env:USERDNSDOMAIN

Clean up upgrade files to free disk space:

Dism /online /Cleanup-Image /StartComponentCleanup /ResetBase
Cleanmgr /sagerun:1

Update Windows and install latest drivers:

Get-WUInstall -AcceptAll -Install
Get-WmiObject Win32_PnPEntity | Where-Object{$_.ConfigManagerErrorCode -ne 0} | Select-Object Name, DeviceID

Document the successful upgrade:

$UpgradeLog = @{
    "UpgradeDate" = Get-Date
    "SourceVersion" = "Previous version from documentation"
    "TargetVersion" = (Get-WmiObject Win32_OperatingSystem).Caption
    "UpgradeMethod" = "In-place upgrade"
}
$UpgradeLog | ConvertTo-Json | Out-File -FilePath C:\Temp\upgrade-log.json