Complete Guide to In-Place Upgrade for Windows Server 2025

Microsoft has officially entered a new era with Windows Server 2025, and with it comes the invaluable option of performing in-place upgrades from Windows Server 2012 R2 or later versions. If you’re an IT professional thinking of upgrading your existing Windows Server infrastructure, this in-depth guide will walk you through the important prerequisites, the actual steps to upgrade using the command line, and the crucial post-upgrade tasks.
Let’s dive in and explore how this upgrade process works, why Microsoft introduced some of these features, and what they mean for IT environments in the long term!

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What Exactly is an In-Place Upgrade?​

Unlike a clean installation, an in-place upgrade lets you preserve all server roles, features, and settings on an existing server while installing a more recent OS version. This ensures minimal downtime and avoids the repetitive process of reinstalling applications or reconfiguring system settings from scratch.
Now, here’s the exciting part: Microsoft fully supports in-place upgrades to Windows Server 2025 from operating systems as old as Windows Server 2012 R2. This compatibility makes it easier for IT teams operating legacy systems to modernize their infrastructure without needing extensive migrations or rebuilds.

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Before You Start: Prerequisites & Preparations​

You wouldn’t jump into a Formula 1 race without checking your car first, would you? Ensuring your server is prepared is crucial for a successful upgrade. Here are the key steps:

1. Ensure You Have the Correct ISO File​

• Make sure the ISO contains the edition of Windows Server 2025 you’ll upgrade to—such as Standard or Datacenter.
• Verify that your edition aligns with your activation mechanism:
• Use a product activation key for standalone servers.
• Use the existing Key Management Services (KMS) if your organization already handles activations centrally.

2. Server Diagnostics: Collect System Information​

Before clicking anything, run diagnostics to collect critical data about your current system. You’ll need this for troubleshooting in case something goes sideways. Open PowerShell and use the following commands to export system information:

powershell

   Get-ComputerInfo -Property WindowsBuildLabEx,WindowsEditionID | Out-File -FilePath .\computerinfo.txt

   systeminfo.exe | Out-File -FilePath systeminfo.txt

   ipconfig /all | Out-File -FilePath ipconfig.txt

These commands can save you hours of troubleshooting if the upgrade doesn’t go as planned.

3. Create Backups!​

It almost goes without saying, but make sure you have full system backups and verify their integrity. Use tools like Windows Server Backup, or third-party services, to create an image of your server that you can easily restore if needed.

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Stage 1: Running the In-Place Upgrade​

Once the groundwork is set, it’s time for the fun part—running Windows Setup. Let’s use Hyper-V Manager as an example to mount the ISO, although the same method applies for physical servers.

Step-by-Step Command-Line Instructions​

• Open PowerShell with Admin Privileges:
• Right-click the Start Button and select Windows PowerShell (Admin).
• Navigate to the Setup Drive:
• Assuming your ISO is mounted to D:, type:
  

  powershell
  
       D:

• Use dir to confirm that setup.exe exists in the directory:
  

  powershell
  
       dir

• Run Windows Setup Silently:
  Execute the following command to launch an automated, unattended setup:
  

  powershell
  
     ./setup.exe /auto upgrade /quiet /imageindex 4 /DynamicUpdate Disable /Compat IgnoreWarning /eula accept

  Let’s break this command down:
• /auto upgrade: Performs the upgrade while preserving current server roles and applications.
• /quiet: Runs the installation without popping up prompts.
• /imageindex 4: Specifies the correct image from the ISO. For instance:
• 1 = Standard (Core), 2 = Standard (Desktop Experience), 3 = Datacenter (Core), 4 = Datacenter (Desktop Experience).
• /DynamicUpdate Disable: Skips downloading updated setup files.
• /Compat IgnoreWarning: Ignores compatibility warnings unless they are critical.
• /eula accept: Automatically accepts Microsoft’s End-User License Agreement (EULA).

Once done, Windows Setup will take over, restart the server, and upgrade your OS offline. When complete, you will arrive at the updated Windows Server 2025 login screen.

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Stage 2: Post-Upgrade Actions​

Breathing a sigh of relief because the upgrade is done? Not so fast! There are still post-upgrade checks that ensure your system remains functional.

1. Check for Errors​

Open Event Viewer and browse error reports to ensure no surprises cropped up during the installation. Focus primarily on:

• Critical Errors
• OS Compatibility Warnings
• Anything mentioning driver conflicts or service failures.

2. Run Windows Update for Patches​

Head back into the Terminal or PowerShell to install the latest security and quality updates:

powershell

   sconfig

Once the Server Config interface pops up, choose:

• 6) Install Updates
• Follow with 1) All quality updates.

Keep repeating the update/reboot cycle until Windows Update shows no new updates.

3. Verify the Upgrade​

Run PowerShell commands like the one below to confirm that your domain controller or server reflects the updated OS version:

Get-ADDomainController | Select Name, OperatingSystem

This ensures your roles and features carried over without any issues.

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Why In-Place Upgrades Matter for Modern IT​

As IT environments scale up and adapt to hybrid cloud setups, simplifying upgrades is more important than ever. Windows Server 2025 introduces a host of new features aimed specifically at scalability, such as enhanced container performance, better integration with Azure, and improved endpoint security measures. Here’s why this matters:

• Minimized Downtime: You can transition to a modern OS while avoiding productivity-killing outages.
• Cost Savings: Avoid sinking money into new hardware or fresh server builds.
• Security Assurance: With cyberthreats ramping up, staying on the latest version ensures access to advanced defense mechanisms.

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Final Thoughts​

Performing an in-place upgrade to Windows Server 2025 is like taking your reliable old car, swapping the engine for a turbocharged version, and fine-tuning everything without repainting it. The process respects your existing configurations while unlocking the power and security of Microsoft’s latest server innovations.
However, it’s critical to approach the upgrade with preparation, caution, and the proper tools. Diagnostic commands, careful mounting of ISOs, automated silent installs, and thorough post-upgrade verification are the keys to a smooth transition.
So, IT pros—set your upgrades in motion and bring your servers into the next era of functionality with Microsoft’s Windows Server 2025! Make sure to discuss your experience in the comments section. Did you hit any snags? Let’s troubleshoot together on WindowsForum.com!

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Source: Petri IT Knowledgebase https://petri.com/in-place-upgrade-to-windows-server-2025/