Windows Server 2016 end of support: what to do before 12 January 2027?
Quick answer
Extended support for Windows Server 2016 ends on 12 January 2027: the server keeps working, but no longer receives free security updates. Three paths: migrate to Windows Server 2025 (supported until 14 November 2034) or 2022 (until 14 October 2031), subscribe to the paid Extended Security Updates (ESU), reserved for customers with Software Assurance, or move part of the services to the cloud.
- Date: 12 January 2027, the last free security update for Windows Server 2016.
- What does not change: the server starts and serves its users as before. The risk grows with every vulnerability found after that date.
- Licences to plan: the new version is licensed per core (at least 16 per server) and needs CALs of the same version or newer. A 2016 CAL does not give access to a 2025 server.
- ESU: up to three years of security updates through Azure Arc, billed from 13 January 2027, reserved for Standard and Datacenter editions under Software Assurance (or SPLA or subscription licences).
What changes on 12 January 2027
Windows Server 2016 follows Microsoft’s Fixed Lifecycle Policy: five years of mainstream support, then five years of extended support. Mainstream support ended on 11 January 2022; extended support, which still delivered security updates, ends on 12 January 2027.
| Version | End of mainstream support | End of extended support | Status on 6 November 2026 |
|---|---|---|---|
| Windows Server 2016 | 11 January 2022 | 12 January 2027 | Last weeks of updates |
| Windows Server 2019 | 9 January 2024 | 9 January 2029 | Extended support |
| Windows Server 2022 | 13 October 2026 | 14 October 2031 | Extended support since 13 October 2026 |
| Windows Server 2025 | 13 November 2029 | 14 November 2034 | Mainstream support |
After 12 January 2027: no more free security updates, no more Microsoft technical support, and software vendors may stop certifying their products on this system.
What you risk if you do nothing
- Vulnerabilities that stay open. The risk is highest for a server exposed to the internet: published Remote Desktop, email, VPN, website.
- Business software that stops following: accounting, sales management or backup software may require a Windows Server version that is still supported.
- A data security obligation: the GDPR requires security measures suited to the risk. An unpatched server holding personal data becomes hard to justify.
- Insurance or customer requirements: some cyber insurance policies or specifications require up-to-date systems. Check yours.
Your options
| Option | Who it is for | What you need to know |
|---|---|---|
| Migrate to Windows Server 2025 | New server or reinstallation, compatible software | Latest version, supported until 14 November 2034. Per-core licences + 2025 CALs. |
| Migrate to Windows Server 2022 | Business software validated on 2022 but not yet on 2025 | Supported until 14 October 2031. A 2025 licence also lets you install 2022 (downgrade rights). |
| Subscribe to ESU through Azure Arc | Migration impossible before January 2027 | Critical and important security updates, for up to three years. Software Assurance required, monthly billing per core. |
| Move part of the services to the cloud | Simple files and email, small team | Microsoft 365 or Azure can replace some roles; the rest of the server still has to be dealt with. |
| Do nothing | — | Not recommended: the server works but is no longer protected. |
2022 or 2025: which one should replace 2016?
For a new server, Windows Server 2025 gives three more years of support than 2022 and is licensed the same way. Keep 2022 only if a business application is not yet validated on 2025: ask its vendor for the list of supported versions. The detailed comparison is in Windows Server 2022 or 2025.
Licences to plan for the migration
- The server licence: all physical cores are licensed, with at least 8 core licences per processor and 16 per server, sold in packs of 2 or 16.
- Standard or Datacenter: Standard allows the physical server and 2 virtual machines; Datacenter, an unlimited number of virtual machines. Beyond 2 virtual machines with Standard, all cores must be licensed again.
- CALs: one per user or device accessing the server, of the server’s version or newer. Your 2016 CALs do not cover a 2022 or 2025 server.
- RDS CALs: if your staff work over Remote Desktop, an RDS CAL of the new version is needed on top of the Windows Server CAL. See RDS CALs per user or per device.
- Windows Server Essentials: for up to 25 users and 50 devices, on a server with a single processor of up to 10 cores, with no CALs. It is sold only with a new server (manufacturer channel) and does not include Remote Desktop for users.
For the figures in your case: the Windows Server licence calculator. The detailed rules are in Windows Server: core and CAL licensing.
Migration in six steps
- Take inventory: installed roles (Active Directory domain controller, file server, printing, Remote Desktop, DHCP, DNS), applications, virtual machines, shares, scheduled tasks, backups, and the number of users and devices that connect.
- Check compatibility of each business application with the target version with its vendor, and note the database versions (SQL Server) in use.
- Choose the hardware or virtualisation: new physical server, virtual machine on an existing host, or hosting. The number of physical cores drives the licence cost.
- Plan the licences: cores, edition, CALs and RDS CALs of the target version, with the calculator.
- Migrate side by side: install the new server next to the old one, add a domain controller and transfer the roles, move the files (Microsoft provides Storage Migration Service in Windows Admin Center), then printers and applications. Test each step before moving on.
- Switch over and retire the old server: check the new server’s backup, demote the old domain controller, remove it from the network, then wipe its disks before recycling or reselling it.
Extended Security Updates (ESU): the exact conditions
| Point | What Microsoft says |
|---|---|
| Availability | Announced on 25 February 2026, available through Azure Arc since 6 August 2026 |
| Contents | Critical and important security updates; no new features and no non-security fixes |
| Retention | Up to three years after end of support, i.e. until January 2030 |
| Editions | Standard and Datacenter |
| Licensing condition | Active Software Assurance under a volume licensing programme, except for SPLA or Windows Server subscription licences |
| How it works | Server connected to Azure Arc (agent 1.62 or newer), monthly billing per core from 13 January 2027, can be cancelled |
ESU buys time, not a lasting solution: it is paid every month and ends in 2030. If your server has no Software Assurance, this option is not open to you: you need to migrate.
The most common mistakes
- Reusing 2016 CALs on a 2022 or 2025 server: a CAL gives access to its own version and earlier ones, never to later ones.
- Buying 8 core licences for a small 8-core server: the minimum is 16 per server.
- Running 3 or 4 virtual machines with a single Standard licence.
- Forgetting the Remote Desktop RDS CALs, or keeping 2016 RDS CALs for a 2025 host.
- Leaving the old domain controller running “just in case”, unpatched, on the network.
- Starting in December: a server migration takes preparation, especially with business software to validate.
What Licenciel can do
We supply Windows Server licences and CALs with an invoice, and a technician checks the quantities with you before you buy. For a full project (server, CALs, Remote Desktop, workstations), request a quote: we reply within 24 business hours.
Frequently asked questions
Will Windows Server 2016 stop working on 12 January 2027?
No. It keeps starting and serving its users, but no longer receives free security updates after that date.
Can you still get security updates after 2027?
Yes, with Extended Security Updates (ESU) through Azure Arc: up to three years, for the Standard and Datacenter editions, provided you have Software Assurance (or SPLA or subscription licences). They are billed monthly per core from 13 January 2027.
Which version should I migrate to?
Windows Server 2025 for a new server: it is supported until 14 November 2034. Windows Server 2022, supported until 14 October 2031, remains a good choice if a business application is not yet validated on 2025.
Do my 2016 CALs work with Windows Server 2025?
No. A CAL gives access to the server version it was bought for and earlier versions, not later ones. A 2025 server needs 2025 CALs.
Can I install Windows Server 2022 with a 2025 licence?
Yes, 2025 volume licences and manufacturer (OEM) licences include downgrade rights to an earlier supported version. Microsoft does not necessarily provide the installation media or the key for the older version.
Can Windows Server Essentials replace my 2016 server?
Yes if you have at most 25 users and 50 devices, a server with a single processor of up to 10 cores, and no need for Remote Desktop for users. Essentials needs no CALs, but it is sold only with a new server.
How many core licences for a small server?
At least 16 core licences per server, even for a 4- or 8-core processor, and at least 8 per physical processor.
What should I do with the old server after the migration?
Demote the domain controller properly, remove the server from the network, then securely wipe its disks before recycling or reselling it.
Going further
- Windows Server licence calculator
- Core and CAL licensing
- Windows Server 2022 or 2025
- RDS CALs
- Licences for businesses
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Sources
- Microsoft · Windows Server 2016 lifecycle
- Microsoft · Planning ahead for Windows Server 2016 end of support, 25 February 2026
- Microsoft Learn · Prepare to deliver Extended Security Updates through Azure Arc
- Microsoft · Windows Server 2025 Licensing Guidance (in English)
- Microsoft Learn · Storage Migration Service