About media-based upgrade to Windows Server 2025

With N-4 media based upgrades, you can upgrade your organization’s physical devices and virtual machines directly from Windows Server 2012R2, Windows Server 2016, Windows Server 2019, or Windows Server 2022 to Windows Server 2025 in one hop using the Windows Server 2025 media. Running Windows Server 2025 setup enables customers to either upgrade or clean install Windows Server 2025. This process takes under an hour per server, depending on the capabilities of the server and the applications installed on it.

(BTW, “Upgrade” has several synonyms: In-place Upgrade and Feature Update – they all refer to the same process which is described here.)

Upgrading Physical or Virtual

Before diving into the details of upgrading to Windows Server 2025, it's helpful to consider several key factors such as whether you're upgrading a physical server or a virtual machine. Let's begin with virtual machines: If your server is running Hyper-V, in-place upgrades are straightforward since the process will automatically update Hyper-V drivers with the new operating system. For those using non-Microsoft virtualization platforms, it is crucial to update guest drivers from that platform before starting the upgrade to Windows Server 2025. Outdated virtualization drivers are a common reason for support requests, so updating them in advance can help you avoid potential issues.

The second scenario involves upgrading physical servers, which can be a bit more complicated. If your server runs Windows Server 2012 R2, it was probably purchased around 2010 or 2011—meaning it's now about 15 years old. While the CPU and motherboard might still work, it's essential to check every component, including network adapters, host bus adapters, storage controllers, and any devices installed in the PCIe slots. Make sure all add-in cards are compatible with Windows Server 2025 and that drivers are available. If you find some components aren't compatible, this could be a good opportunity to move workloads to the cloud, invest in new hardware, or consider virtualizing these workloads to simplify future upgrades.

Planning for the upgrade

Carefully planning the upgrade process will minimize downtime:

• Check that your hardware and application vendors support Windows Server 2025 – we’ve worked with a very broad range of hardware and application vendors to ensure support and compatibility.
• Checkpoints and Backups - Whenever you're performing an operating system upgrade, it's a good idea to make sure you've got a physical backup or a VM checkpoint just in case of unforeseen issues. If you're using a VM it's easy, take a snapshot of your existing virtual machine so that you can revert in the case that you need to if you're doing a physical server of course make sure you have a backup as well. the upgrade is not 100% perfect and can fail, so a backup is strongly recommended – as is a backup restore test.
• Backup storage – backups should be stored on a different device or a remote location – not on the device that is being upgraded to Windows Server 2025.
• Test the upgrade process on a test device in your environment to gain experience with the process.
• Schedule a maintenance Window for your customers / users and inform them that their data and applications will be offline.

o   Although the average time to upgrade a server is typically an hour, the process may take several hours – so set expectations appropriately.

• Plan to stop all applications on the server before backing up the server and applications.

Windows Server running Active Directory Domain Services

In place upgrades for Windows Server 2025 can be used for any Windows Server role except for Active Directory. Remember: domain controllers are special. Active Directory is a multi-master directory service which means that changes to the directory data can be made on any domain controller within the domain and those changes are then replicated to other domain controllers to ensure that there's no single point of failure while providing redundancy and high availability. Because Active Directory is a multi-master service, the process for upgrading domain controllers is the same as it has been for decades.

• Step 1: Setup new domain controller running Windows Server 2025
• Step 2: Synchronize new domain controllers with existing domain controllers
• Step 3: Turn off old domain controllers
• Step 4: Raise the Forest Functional Level and Domain Functional Level

You can find detailed documentation for upgrading domain controllers here.

Do I need to purchase a Windows Server 2025 product key?

Volume License customers with Software Assurance have upgrade rights and should be able to upgrade to Windows Server 2025 and activate when their KMS is configured. Either a Window Server 2025 product key or a correctly configured Key Management Server (KMS) is needed to Activate Windows Server 2025 devices. Customer Support Services require devices to be activated to receive product support.

Windows Server Upgrade Walk-through

When you have completed the preparation steps above, and you’re ready to upgrade a Windows Server device, the steps are relatively easy:

1. First, check that you are running Windows Server 2012 R2, 2016, 2019, or 2022 by running winver:

 

 

2. Run Windows Server 2025 setup from the ISO or extracted ISO media:

 

 

3. By default, setup will start by attempting to download updates to the setup process to ensure a smoother upgrade experience:

 

 

4. You will be prompted for the version of Windows Server that you’d like to upgrade to – in this case, Windows Server 2025 Datacenter (Desktop Experience) has been selected:

 

 

5. Next, you will be asked to agree to the license terms:

 

 

6. To upgrade the server, select the “Keep files, settings, and apps” radio button and press Next:

 

 

7. Setup will fetch any available updates for the upgrade process…

 

 

8. After setup have downloaded updates for the upgrade process, it will check that you want to upgrade your server to Windows Server 2025 – select Install:

 

 

9. Setup will attempt to upgrade your server to Windows Server 2025 and migrate your applications, settings, and user profiles. When completed, the server will restart:

 

 

10. Note that the restart will take several minutes to complete the final phases of upgrade. When the server restarts, you will be asked if you want to Include Optional or just Required only telemetry data back to Microsoft. Microsoft uses this data to improve Windows Server. Select the option that you prefer and press Accept:

 

 

11. When Windows Server 2025 starts with the Desktop Experience or ServerCore, you can check the version using winver:

 

 

12. Check for updates using the Settings Dialog | Windows Update (or WSUS or Update Management Software) – to download and install the Latest Cumulative Updates (LCU) packages. Install the LCUs and Restart:

 

 

13. After all LCUs have been installed and the server has been rebooted, verify that applications start correctly and all components and devices are working as expected.
14. If the upgrade to Windows Server does not succeed:
    • You can troubleshoot upgrade issues by examining the setup logs which are in the C:\Windows\Panther directory. There is a setup log parsing utility called SetupDiag that can be downloaded here: SetupDiag | Microsoft Learn.
    • Restore the previous version of Windows Server from the backup media.

We hope you enjoy using Windows Server 2025 and have found the Upgrade process to be easy!