Upgrading to Windows Server 2025 from Windows Server 2022 using Media (ISO)

The adoption of Windows Server 2025 has been remarkable, and we are truly grateful for the overwhelming response. A big thank you to everyone on the Windows Server team for their hard work.

Windows Server 2025 brings several major improvements, including features like hot patching, Hyper-V GPU-P support, enhancements to Active Directory, new security measures, better storage performance, and improved scalability. Additionally, we’ve focused on simplifying the upgrade process, making this release the easiest yet, with support for N-4 upgrades.

About media-based upgrade to Windows Server 2025

With N-4 media-based upgrades, organizations can directly upgrade physical servers and virtual machines from Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, or Windows Server 2022 to Windows Server 2025 in a single step using the Windows Server 2025 installation media.

Running the Windows Server 2025 setup gives administrators the option to either perform an in-place upgrade or carry out a clean installation. In most cases, the upgrade process completes in under an hour per server, depending on the system’s hardware capabilities and the applications installed.

Upgrading Physical or Virtual

Before diving into the Windows Server 2025 upgrade process, it’s important to evaluate a few key factors starting with whether you’re upgrading a virtual machine or a physical server.

For virtual machines, the process is generally straightforward. If your environment is running Hyper-V, in-place upgrades are seamless, as the setup automatically updates Hyper-V drivers alongside the new operating system. However, if you’re using a non-Microsoft virtualization platform, it’s essential to update the guest drivers provided by that platform before initiating the upgrade. Outdated virtualization drivers are a common source of upgrade issues, so addressing them in advance can help avoid complications.

Upgrading physical servers, on the other hand, requires more careful planning. Systems running Windows Server 2012 R2 are often over a decade old, meaning the hardware may be nearing the end of its lifecycle. While core components like the CPU and motherboard might still function, it’s critical to verify compatibility across all hardware elements—including network adapters, host bus adapters, storage controllers, and any PCIe expansion cards. Ensure that compatible drivers for Windows Server 2025 are available for all components.

If compatibility gaps are identified, this may be the right time to modernize your infrastructure—whether by migrating workloads to the cloud, investing in newer hardware, or virtualizing existing workloads to make future upgrades easier and more efficient.

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.

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:

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

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

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:

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

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

Setup will fetch any available updates for the upgrade process…

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:

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:

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:

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

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!