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Windows Server 2016 Support Ends January 12, 2027: What a Small Business Should Do Now

Writer: Dane Gray
Dane Gray
19 minutes ago
6 min read

By Dane Gray, 24uNet. Last reviewed November 9, 2026.

Short answer: Microsoft ends extended support for Windows Server 2016 on January 12, 2027. The server keeps running but receives no security updates. Small businesses can upgrade to Windows Server 2025, move the work off the server, or buy temporary Extended Security Updates. With about nine weeks left, now is the time to decide.

What happens on January 12, 2027?

Nothing breaks that morning. Your server will still start, your shared drives will still open and your accounting program will still run.

What changes is that Microsoft stops fixing it. Microsoft says that after the end-of-support date, devices on these older products no longer receive Windows security updates, non-security updates, bug fixes or technical support. This applies to the Standard, Datacenter and Essentials editions of Windows Server 2016.

That matters because a server holds the things your business can't afford to lose or leak: client files, payroll records, the accounting database. New flaws get found in every operating system over time. After the cutoff, an unsupported server doesn't get the fixes, so the list of open problems only grows.

Step 1: Find every Windows Server 2016 machine

Start with a plain inventory. Most small offices have more servers than anyone remembers.

  • The main file server, usually in a closet or under a desk

  • A domain controller that handles sign-ins for the office

  • A server that runs one line-of-business program, such as accounting or practice management

  • Virtual machines that run on a larger server

  • An older server that was "just kept for one old program"

For each one, write down what it does, who depends on it, what software the vendor says it supports, and how old the hardware is. That list drives every decision that follows.

Step 2: Choose a path for each server

You don't have to pick one answer for the whole office. Each server can go a different way.

Option A: Upgrade to Windows Server 2025

Microsoft recommends upgrading to Windows Server 2025. Microsoft's upgrade table shows that an in-place upgrade from Windows Server 2016 straight to 2025 is supported when you use installation media, on a server that isn't clustered. An in-place upgrade keeps your settings, roles and data, but the server needs downtime and a restart or several.

Three cautions from Microsoft's own documentation:

  • Back up first, and test the restore. Microsoft's prerequisites call for a full backup and a restore test before any in-place upgrade.

  • Domain controllers are different. Microsoft says not to use an in-place upgrade on servers that run Active Directory Domain Services. The recommended route is a clean install: promote a new domain controller, then retire the old one.

  • Check your applications. Your software vendor has to support the new Windows version. Ask before you schedule anything.

Licensing is the part owners miss. Microsoft notes that each Windows Server upgrade requires its own license. Access licenses matter too: a Windows Server 2025 client access license (CAL) covers earlier versions, but a 2022 or 2019 CAL does not cover a 2025 server. Plan for the licenses, not just the install.

Option B: Move the work off the server

Sometimes the right answer is to retire the server. If it mostly holds shared files, those files may be better off in SharePoint or in Azure Files, with the old box retired. If it runs one program, the program's maker may offer a hosted version that removes the server entirely.

If you are an existing 24uNet client, our Managed File Services (Azure) option is one way to do this for file servers. It pairs your Windows file server with Azure Files and is planned, set up and managed by us. It is quoted for your environment, and the quote spells out fit and scope.

Option C: Buy Extended Security Updates as a bridge

If a server can't be upgraded or moved by January 12, Microsoft offers Extended Security Updates (ESUs) for Windows Server 2016. Here's what Microsoft has published:

  • ESUs cover Critical and Important security updates only. They don't include new features or non-security fixes.

  • Coverage can run up to three years, through January 2030.

  • They're delivered through Azure Arc. The server has to be connected to Azure Arc, and Microsoft's docs say you can configure ESUs in the Azure portal starting August 3, 2026.

  • Billing for ESUs through Azure Arc begins January 13, 2027.

  • Purchasing generally requires Software Assurance through a volume licensing program. Servers licensed through SPLA or a server subscription don't need Software Assurance.

Microsoft itself calls ESUs a temporary bridge, not a long-term plan. They're useful when a business-critical application needs more time, and not much else.

Option D: Do nothing

This is a choice, even if nobody makes it on purpose. A server that has lost support and holds client data is hard to defend to an insurer, a client or an auditor. Check your cyber insurance application and any client security questionnaires for questions about unsupported software before you decide this is acceptable.

A simple nine-week plan

Here's a plan that fits the calendar. Adjust it for your business.

  1. Weeks 1 and 2 (now): Take the inventory. Ask each software vendor which Windows Server versions they support.

  2. Weeks 3 and 4: Pick Option A, B or C for each server. Price the licenses and any new hardware.

  3. Weeks 5 to 7: Back up, test the restore, and run the work in a quiet window. For a domain controller, build the new one beside the old one.

  4. Weeks 8 and 9: Test everything with the people who use it. Keep the old server powered but isolated until you're sure.

Avoid scheduling the cutover for the last week of December. Holidays are a bad time to find out a printer, a scanner or an old application didn't survive the move.

How 24uNet helps

A server upgrade is a defined project, which fits a Service Authorization: a written list of the services your business selects, drafted and reviewed before work begins. Day-to-day Windows and application patching is part of BusinessCare, our managed IT and security service. A server that can no longer be patched is a gap a patching routine can't close, which is why the replacement plan comes first. Your business provides and pays for its own Microsoft licensing, including server licenses and access licenses. We help you size and manage what you buy.

For a wider list of year-end items, including backups and restore tests, see our year-end IT and security checklist and our guide to business backup services for Denver and Boulder.

Frequently asked questions

When does Windows Server 2016 reach end of support?

Extended support for Windows Server 2016 ends on January 12, 2027. After that date Microsoft no longer provides security updates, bug fixes or technical support for it unless you buy Extended Security Updates.

Will my Windows Server 2016 server stop working on that date?

No. It keeps running. It just stops receiving security updates, so new vulnerabilities found afterward stay open.

Can I buy extra security updates for Windows Server 2016?

Yes. Microsoft offers Extended Security Updates through Azure Arc for up to three years, through January 2030. They cover Critical and Important security updates only, and purchase generally requires Software Assurance unless the server is licensed through SPLA or a server subscription.

Can I upgrade Windows Server 2016 to Windows Server 2025 in place?

Yes, on a server that isn't clustered, using installation media. Back up and test the restore first. Microsoft advises against in-place upgrades on Active Directory domain controllers and recommends promoting a new one instead.

Do I need new client access licenses for Windows Server 2025?

Generally yes. A 2025 access license covers 2025 and earlier versions, but older access licenses don't cover a 2025 server. Check your licensing before you buy.

Talk to us before January

If you have a Windows Server 2016 machine and aren't sure which path fits, tell us what it does and we'll help you sort it out. For a defined upgrade or move, start with a Service Authorization. Denver (303) 468-5515 · College Station (979) 256-5100.

Sources (verified November 9, 2026)

Photo: Pexels 442150, "Electronics Engineer Fixing Cables on Server," Field Engineer. Pexels License.

 
 
 

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