Abstract:
Microsoft reminds organizations still running Windows Server 2012 and Windows Server 2012 R2 in production environments that the Extended Security Update (ESU) program for these two systems has ended on October 13, 2026. Microsoft has since stopped providing security updates for them. Regular extended support for the two server systems has been terminated as early as October 10, 2023. The three-year ESU is only a transition period and mainly provides security updates rated as "important" or "critical" and does not include new features, non-security fixes or design changes.
This means that unmigrated servers will continue to run, but will lose subsequent security patches and related support released by Microsoft, making them more difficult to maintain over time and increasing security and compliance risks. In a note released on October 14, Microsoft recommended that administrators first inventory data centers, edge devices and cloud environments to find servers that are still running old systems, and then clarify the applications, databases and other dependencies they carry to avoid affecting key businesses during migration.
The subsequent paths listed by Microsoft include upgrading to a still supported version of Windows Server, migrating workloads to Azure, transforming applications on Azure, or adopting a hybrid solution that combines on-premises and cloud. For organizations that wish to continue local deployment, they can create a new supported version server and migrate applications and data, or they can evaluate in-place upgrades. Microsoft documentation states that starting from Windows Server 2025, non-clustered servers support upgrades across up to four versions at a time, such as a direct upgrade from Windows Server 2012 R2 to version 2025. The specifics still need to be planned according to the environment and application compatibility.
On-premises customers who previously purchased ESU can manage related updates through Azure Arc; customers who have migrated to Azure can obtain ESU for free within the specified period. However, none of these arrangements extended the final deadline for 2012 and 2012 R2. Microsoft confirmed that the last round of ESU coverage had expired on October 13. The company recommends arranging the migration sequence according to business criticality and risk, and developing a transformation plan with Microsoft account teams or partners.
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