On January 12, 2027, Windows Server 2016 reaches the end of extended support. After that date, Microsoft stops releasing security updates for it. Your servers will keep running, but every vulnerability discovered from then on stays open permanently.
If you still have Windows Server 2016 in production, that leaves about three months to plan, test and upgrade. Here's what you need to know and how to approach it without disrupting your business.
What "end of support" actually means
Microsoft supports each Windows Server release in two phases. Mainstream support includes feature changes and non-security fixes. Extended support includes security updates only. Windows Server 2016 left mainstream support in January 2022, and extended support ends on January 12, 2027.
After that:
- No more security patches. New vulnerabilities in the operating system, IIS, Remote Desktop Services and built-in components will not be fixed.
- Compliance gets harder. Frameworks like PCI DSS require you to apply security patches promptly, which an unsupported system can't do. Auditors and cyber insurance questionnaires routinely ask about unsupported operating systems. We covered the insurance side in things you can do to lower your cyber insurance premiums.
- Vendor support dries up. Software vendors stop certifying their applications on unsupported platforms, so you may lose support for the very application the server exists to run.
Windows Server support dates at a glance
| Version | Mainstream support ends | Extended (security) support ends |
|---|---|---|
| Windows Server 2016 | January 11, 2022 | January 12, 2027 |
| Windows Server 2019 | January 9, 2024 | January 9, 2029 |
| Windows Server 2022 | October 13, 2026 | October 14, 2031 |
| Windows Server 2025 | Into the 2030s | Into the 2030s |
Always confirm dates on Microsoft's official lifecycle pages before you plan around them.
Notice that Windows Server 2019 has barely two years of security support left after 2016 ends. If you're upgrading anyway, it usually makes sense to go straight to Windows Server 2025 rather than paying for the same project twice.
Don't forget SQL Server
Many Windows Server 2016 machines also run SQL Server 2016, whose extended support already ended in July 2026. If that describes your environment, the database is already unpatched. Plan the SQL Server upgrade as part of the same project, since it often has more compatibility testing than the operating system itself.
Your three options
1. In-place upgrade
Windows Server 2025 supports upgrading in place from Windows Server 2012 R2 and later, so a 2016 server can go directly to 2025. This keeps the server's name, IP address, roles and installed applications.
It's the fastest route, but it carries over years of accumulated configuration drift. It works best for straightforward servers, such as a single application or file server, with a full backup and a tested rollback plan.
2. Build new and migrate
Stand up a fresh Windows Server 2025 machine, install and configure the application cleanly, migrate the data, then cut over. This takes longer, but you end up with a clean, documented server, and the old one stays available as a fallback until you're confident.
For domain controllers, SQL Server and complex line-of-business applications, this is usually the right choice.
3. Retire or consolidate
An end-of-support deadline is a good moment to ask whether every server still needs to exist. We often find workloads that can be consolidated onto fewer, newer servers, or moved to a managed cloud server that's cheaper to run. See signs that you need to invest in a server upgrade.
Budget for licensing
Licensing is the part of a Windows upgrade that most often surprises people:
- Windows Server is licensed per core, with a minimum of 16 core licenses per server. A move to newer hardware with more cores can change your licensing cost.
- Client Access Licenses (CALs) must match or exceed the server version. Users connecting to a Windows Server 2025 machine need 2025 CALs, and that includes Remote Desktop Services CALs if you run terminal servers. Older 2016 CALs don't carry forward.
- SQL Server licenses follow their own rules, so check whether your current licenses cover the version you're moving to.
A step-by-step upgrade plan
- Inventory. List every Windows Server 2016 machine, what it runs, who depends on it and whether it's internet-facing. Internet-facing servers go to the top of the list.
- Check application compatibility. Confirm with each software vendor that their current version supports Windows Server 2025, and whether you need to upgrade the application too.
- Choose a path per server: in-place, rebuild, or retire.
- Back up and snapshot. Take a full, verified backup before you touch anything, and test that you can restore it.
- Test first. Clone the server and rehearse the upgrade on the copy. Problems found in a rehearsal cost nothing.
- Schedule a maintenance window and tell your users. Most upgrades fit in an evening or a weekend.
- Upgrade, verify, monitor. Check every role, service and scheduled task afterward, then watch the server closely for the first few days.
- Update licensing and documentation before the old server is decommissioned.
Need a hand?
We've been upgrading and managing Windows servers since 2001, and our technicians are equally comfortable with Windows and Linux. We can plan and carry out your upgrade, including the SQL Server and Remote Desktop pieces, and keep your new servers patched from then on with proactive server management. For a one-off project, our hourly support is a good fit.
January will arrive quickly. Contact us to schedule your upgrade before the deadline.