
How to Install Windows Server 2025: Step-by-Step
Learn how to install Windows Server 2025 from USB or ISO, choose Standard or Datacenter, select Server Core or Desktop Experience, configure storage, and complete
Windows Server / How to Upgrade Windows Server 2016 to Windows Server 2025
You can now upgrade Windows Server 2016 directly to Windows Server 2025 on a qualifying nonclustered system. Microsoft expanded the supported in-place upgrade range with Windows Server 2025, allowing direct upgrades from Windows Server 2012 R2 and later when installation media is used. That means a Windows Server 2016 machine does not have to pass through Windows Server 2019 or 2022 first.
That makes the technical path simpler, but Windows Server 2016 deserves more cautious migration planning than a recent server release. It reaches the end of extended support in January 2027, and many organizations still running it are also dealing with aging hardware, old drivers, legacy applications, accumulated configuration and infrastructure roles that may be better migrated than upgraded in place.
For a healthy member server with supported software and hardware, a direct 2016-to-2025 in-place upgrade can be practical. For an old file server, domain controller, application platform or machine due for replacement, a clean Windows Server 2025 deployment followed by workload migration can provide a much safer result.
The operating-system upgrade is therefore only one part of the project. The first decision is whether preserving the existing server is actually desirable.
Yes.
Microsoft’s current upgrade matrix explicitly lists Windows Server 2016 → Windows Server 2025 as a supported in-place upgrade path when you use Windows Server installation media. Starting with Windows Server 2025, nonclustered systems can move up to four versions in a single upgrade.
That is different from older Windows Server guidance, where administrators often planned intermediate-version hops.
There is an important limitation: the Windows Update feature-upgrade method currently supports Windows Server 2019 and Windows Server 2022 as sources for Windows Server 2025. Windows Server 2016 is not listed for that method. A direct Windows Server 2016-to-2025 in-place upgrade should therefore be planned around Windows Server 2025 installation media rather than the Windows Update feature-upgrade path.
This distinction matters because older articles and forum answers may still say that Windows Server 2016 requires an intermediate upgrade. Microsoft’s current official upgrade matrix supersedes that older assumption.
A supported in-place path answers one question:
Can Windows Setup perform the upgrade?
It does not answer:
Should this production workload be upgraded that way?
Windows Server 2016 was released a decade ago. A server that has been in production for much of that period may carry years of application upgrades, configuration changes, old drivers, management agents, abandoned services and hardware dependencies.
Preserving all of that during an in-place upgrade may be convenient, or it may carry technical debt directly into Windows Server 2025.
A clean migration is usually worth serious consideration when:
The newer the source operating system, the more attractive in-place upgrade can be. With Windows Server 2016, migration often deserves equal consideration.
The migration is no longer something organizations should treat as a distant modernization project.
Windows Server 2016 left mainstream support in January 2022 and reaches the end of extended support in January 2027.
That does not mean every 2016 server should be upgraded tomorrow regardless of application risk. It does mean that a server remaining on 2016 should now have a documented retirement, upgrade or replacement plan.
If an old application is preventing migration, identify exactly what the blocker is:
“Legacy application” should be the beginning of the investigation, not the permanent migration strategy.
Windows Server edition and installation type affect what you can preserve during an in-place upgrade.
Microsoft’s current rules state that an upgrade normally retains the existing edition. Standard therefore normally remains Standard, while Datacenter remains Datacenter.
Moving upward from Standard to Datacenter can be supported as part of the upgrade. Moving downward from Datacenter to Standard is not.
You also cannot switch between Server Core and Server with Desktop Experience during an in-place upgrade.
If the Windows Server 2016 source uses Server Core but the Windows Server 2025 design requires Desktop Experience, perform a clean installation or migration instead. The reverse is also true.
Other restrictions include:
Checking those points before the maintenance window is much better than discovering them on the final Setup screen.
Application compatibility matters more when migrating from an older OS generation.
Do not inventory only the visible business application. Capture the whole software stack.
That includes the application itself, database engine, IIS modules, .NET dependencies, Java runtime, backup software, EDR or antivirus, monitoring agents, remote-management software, printer or storage drivers, NIC/HBA tools, hardware-management utilities, scheduled tasks and any custom Windows services.
Also identify what other systems depend on the server.
A Windows Server 2016 machine may still be communicating with:
Windows Server Setup does not validate every business dependency for you.
The upgrade can complete successfully while the application remains unusable.
The correct migration method can change depending on the role.
Microsoft maintains a role-by-role upgrade and migration matrix because some Windows Server roles support both in-place upgrades and migration, while others should use a dedicated migration process.
A member server running a supported application on healthy hardware can be a reasonable direct-upgrade candidate.
If its vendor explicitly supports Windows Server 2025, the backup has been tested and the hardware will remain in service, retaining the existing configuration may save significant rebuilding work.
A straightforward file server can technically be upgraded, but an aging Windows Server 2016 file server is also a strong candidate for side-by-side migration.
Storage Migration Service can inventory a source server, transfer files and configuration to a newer destination and perform a cutover. Microsoft supports Windows Server 2025 as a destination and specifically recommends 2025 when creating a new Azure VM destination through the migration workflow.
A migration can let you modernize the OS, hardware and storage architecture in the same project instead of putting Windows Server 2025 onto an old chassis.
Do not treat a Windows Server 2016 domain controller like an ordinary application server.
Microsoft currently recommends deploying a clean newer Windows Server installation, promoting it to a domain controller and demoting the older DC rather than performing an in-place operating-system upgrade. This approach also delivers the full Active Directory performance and feature improvements associated with newer Windows Server releases.
A typical migration sequence is:
If you deliberately perform an in-place DC upgrade instead, Microsoft requires manual adprep /forestprep and adprep /domainprep preparation. When a new server is promoted, those preparations are integrated into the normal promotion workflow.
A standalone Hyper-V host needs special maintenance preparation because its guests should not remain running during the host operating-system upgrade.
Microsoft’s in-place upgrade guidance instructs administrators to shut down or migrate running VMs before beginning.
For a Windows Server 2016 Hyper-V host, also ask whether upgrading the old host is worthwhile at all.
If new physical hardware is already planned, deploying Windows Server 2025 on new hosts and migrating the VMs may produce a cleaner infrastructure outcome.
Do not apply the generic standalone upgrade procedure to cluster nodes.
Windows Server clusters have their own supported upgrade processes, and Microsoft’s standard direct in-place guidance specifically distinguishes cluster rolling upgrades from ordinary server upgrades. Cluster rolling upgrades move only one Windows Server version at a time.
If Windows Server 2016 belongs to a cluster, build the migration around the cluster-specific documentation and workload support requirements.
Before touching Windows Setup, complete the preparation.
Microsoft’s upgrade documentation specifically calls for a valid product key and activation method and a location outside the server where diagnostic information can be stored.
You should be able to prove what changed after the migration.
From an elevated PowerShell session, capture the current Windows version and edition:
Get-ComputerInfo -Property WindowsBuildLabEx,WindowsEditionID |
Out-File .\computerinfo.txt
Record the system configuration:
systeminfo.exe | Out-File .\systeminfo.txt
Record networking:
ipconfig /all | Out-File .\ipconfig.txt
Store the output somewhere other than the server itself.
For a production system, also record:
This baseline becomes extremely useful if the operating system comes back successfully but one part of the workload does not.
The migration plan should contain more than the sentence “server is backed up.”
A restore test answers questions that backup reports cannot:
Can you actually recover the system?
Do you have the required credentials?
Is the backup repository accessible when the production server is unavailable?
How long will recovery take?
Does application-consistent recovery require additional steps?
Microsoft’s current in-place upgrade guidance emphasizes protecting the OS, applications, data and VMs where applicable before performing the upgrade.
For a ten-year-old Windows Server environment, this is especially important because the original recovery documentation may itself be outdated.
Set a point at which troubleshooting stops and recovery begins.
For example, rollback may be triggered when:
This protects the business from an upgrade turning into an indefinite troubleshooting session.
Side-by-side migration has a particular advantage here. Because the original Windows Server 2016 machine remains intact, rollback can sometimes mean routing the workload back to the old system rather than restoring the entire OS from backup.
If the server has passed compatibility checks and an in-place upgrade is the right design, Windows Server 2025 installation media provides the supported direct route.
Patch Windows Server 2016 to the appropriate current level and reboot if necessary.
Confirm:
Do not begin the OS upgrade while another infrastructure change is unresolved.
Mount the Windows Server 2025 ISO from the existing Windows Server 2016 installation.
Launch:
setup.exe
The direct upgrade should be started from the running Windows Server environment. Microsoft’s current Setup procedure applies to qualifying non-Azure, nonclustered servers running Windows Server 2012 R2 or later.
Do not boot from the ISO if your intention is to preserve the existing applications, settings and roles through an in-place upgrade.
Setup can check for updated installation files.
Internet-connected servers may retrieve installation updates during the process, while managed environments may use media and updates that have already passed change-control testing.
Either can be valid.
What matters is that the method has been decided before production downtime begins.
Setup may request licensing information depending on the media and distribution channel.
The fact that Windows Server 2016 is technically eligible for a direct OS upgrade does not grant Windows Server 2025 licensing rights.
Licensing entitlement, activation and technical upgrade compatibility are separate matters.
Resolve the license and target edition before the maintenance window.
Verify that Setup is targeting the intended edition.
Windows Server 2016 Standard normally upgrades to Windows Server 2025 Standard. Datacenter normally remains Datacenter.
If you deliberately intend to move Standard to Datacenter, verify that decision and the licensing before proceeding.
Do not accidentally use migration downtime as the moment to make an unplanned architecture or edition change.
For an in-place migration, select the option that keeps the existing files, settings and applications.
This is what differentiates the in-place workflow from a clean installation.
If that option is unavailable, stop and investigate.
Possible causes include incompatible media, language mismatch, an unsupported edition or installation-type difference.
Continuing with the wrong Setup mode can turn an upgrade project into a rebuild.
Before selecting Install, verify:
Start the installation only after those conditions are satisfied.
The server will restart multiple times while Windows Setup replaces the operating-system components and migrates the existing configuration forward.
Not under Microsoft’s current installation-media upgrade rules.
Windows Server 2016 can now move directly to Windows Server 2025 on a qualifying nonclustered system.
There can still be situations where an intermediate release becomes relevant, but they are typically driven by workload support rather than Windows Setup itself.
For example, an application vendor might support:
Windows Server 2016 → application version B → Windows Server 2022 → application version C → Windows Server 2025.
In that case, the application upgrade chain is dictating the migration sequence.
Do not add intermediate Windows Server upgrades merely because older guidance said they were required. Equally, do not skip application-specific requirements just because Windows Setup supports the direct OS path.
This is an easy point to miss because Windows Server 2025 can now be offered as a feature update on some earlier Windows Server versions.
Microsoft’s current Windows Update requirements list Windows Server 2019 and Windows Server 2022 as eligible source releases for upgrading to Windows Server 2025 through Windows Update. Windows Server 2016 is not listed.
For Windows Server 2016, plan the direct in-place path using installation media.
This also means instructions written specifically for the Windows Server feature-update policy on 2019 or 2022 should not simply be copied onto a 2016 server.
Reaching the sign-in screen does not complete the migration.
Start with the operating system.
Confirm the installed version and edition. Then compare the system against the baseline captured before the change.
Verify:
Then move on to the actual workload.
A successful ping is not a successful migration.
Test the server from the perspective of the systems and users that depend on it.
For an application server, log into the actual application.
For an IIS server, test the production website or API.
For a file server, access the normal share path from a client and test permissions.
For a database-dependent system, perform a meaningful application transaction.
For a Hyper-V host, verify the virtual networking and storage configuration before returning guests to production.
For infrastructure services, validate them with their role-specific tools rather than assuming that a running Windows service means the role is healthy.
Also confirm:
Only then should the change be considered successful.
Preserve Windows Setup logs before repeatedly changing the machine.
The Windows Setup log directory commonly used for troubleshooting is:
C:\Windows\Panther
Microsoft also provides SetupDiag for analyzing Windows Setup log data.
Compare those logs with the diagnostic information captured from Windows Server 2016 before the migration.
That can help separate:
If the predefined rollback point has already been reached, restore the production workload first and investigate the failed upgrade afterward.
A direct upgrade can save work, but a Windows Server 2016 system is old enough that preserving everything may not be a benefit.
Suppose a physical Windows Server 2016 machine is seven years old and due for replacement within another year.
Upgrading the OS in place puts a modern server release on hardware that still has a short remaining lifecycle.
Deploying Windows Server 2025 on new hardware and migrating the application or role solves both lifecycle problems at once.
Suppose a 2016 file server contains several terabytes of data, old storage drivers, years of shares and outdated hardware.
Storage Migration Service can inventory, copy and cut over applicable file-server workloads to a newer Windows Server destination.
That is often more attractive than preserving every aspect of the old server.
For a DC, the migration answer is clearer.
Microsoft recommends a clean newer server, promotion to domain controller, validation, then demotion of the old DC rather than the normal in-place OS approach.
Suppose a Windows Server 2016 ERP system is business-critical and requires several hours of testing before anyone can be confident that it works on Windows Server 2025.
Building a separate 2025 system lets the team test the application before the final production cutover.
If the migration fails, the Windows Server 2016 production machine can remain intact.
That rollback advantage can justify the additional migration work.
Once Windows Server 2025 is established as the target, choose the edition based on the new architecture, not merely the edition installed on the old server.
A mainly physical server or an environment with relatively limited Windows Server virtualization requirements may naturally lead toward Windows Server 2025 Standard Core-Based.
A virtualization-heavy host or environment whose architecture makes Datacenter licensing and capabilities appropriate should instead evaluate Windows Server 2025 Datacenter Core-Based.
Before purchasing, establish the physical core configuration, intended VM density, edition requirements and relevant access licensing.
Do not calculate the new requirement from CPU threads, vCPUs or the number of VMs alone.
Once Windows Server 2025 is established as the target, choose the edition based on the new architecture, not merely the edition installed on the old server.
A mainly physical server or an environment with relatively limited Windows Server virtualization requirements may naturally lead toward Windows Server 2025 Standard Core-Based.
A virtualization-heavy host or environment whose architecture makes Datacenter licensing and capabilities appropriate should instead evaluate Windows Server 2025 Datacenter Core-Based.
Before purchasing, establish the physical core configuration, intended VM density, edition requirements and relevant access licensing.
Do not calculate the new requirement from CPU threads, vCPUs or the number of VMs alone.
A Windows Server 2016 Standard member server runs one current business application. The application vendor supports Windows Server 2025, the hardware remains supported and a tested bare-metal recovery process exists.
A direct in-place upgrade can be reasonable.
Use Windows Server 2025 installation media, retain the existing applications and settings, and complete workload-level testing before returning the machine to production.
A physical Windows Server 2016 file server has aging storage and no reason to remain on the current hardware.
A side-by-side Windows Server 2025 deployment is usually the cleaner answer.
Migrate files and configuration using the appropriate file-server migration tools, validate access and permissions, then retire the old system after the rollback period.
A Windows Server 2016 server provides DNS, an application service and several undocumented scheduled jobs.
Even though Windows Setup might permit an in-place upgrade, the workload should first be decomposed and documented.
It may be safer to migrate the infrastructure roles and application separately rather than preserving an old multipurpose server exactly as it exists.
Modernization is sometimes more valuable than preservation.
The most important technical fact is straightforward: Windows Server 2016 can currently be upgraded directly to Windows Server 2025 using installation media on a qualifying nonclustered system. An intermediate Windows Server 2019 or 2022 upgrade is not inherently required.
The more important operational question is whether you should use that path.
Choose a direct in-place upgrade when the machine is healthy, the applications and drivers support Windows Server 2025, the hardware still belongs in the target architecture and you have a proven recovery process.
Choose a clean or side-by-side migration when the hardware is old, the workload is poorly documented, rollback must be simple, you need to redesign the server, or the role has a better migration pattern.
For Windows Server 2016 domain controllers, favor the clean-DC promotion and demotion approach recommended by Microsoft. For file servers, evaluate Storage Migration Service. For clusters, use the appropriate cluster-specific procedure rather than the generic standalone upgrade process.
Windows Server 2016 is approaching the end of its normal support lifecycle, so delaying indefinitely is no longer a strong strategy. But urgency should not turn a manageable migration into an untested in-place upgrade.
Inventory the workload, verify compatibility, prove the backup, choose the migration method deliberately and validate the application-not just Windows-before calling the move to Windows Server 2025 complete.

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