.NET 8 and .NET 9 End of Support: Migration Guide for 2026

Learn how to prepare for .NET 8 and 9 end of support in 2026, assess migration risks, plan an upgrade to .NET 10, and estimate project costs.

Microsoft's .NET 8 and .NET 9 support ends in November 2026. Learn how to assess your application, plan a .NET 10 migration, manage compatibility risks, and estimate the effort required to keep your software secure and maintainable.

Microsoft's support window for .NET 8 and .NET 9 closes in November 2026. For businesses running applications on either version, this is an important point to review software security, dependency compatibility, and long-term maintenance plans.The applications will not suddenly stop working when support ends. However, continuing to run an unsupported runtime means losing access to new security fixes and servicing updates for that version. That can increase operational risk and make it harder to maintain a reliable software environment.The right response depends on the application. A modern API with an automated test suite may need a relatively straightforward upgrade. An older enterprise platform with tightly coupled services, outdated libraries, or undocumented business rules can require a much broader modernization effort.This guide explains what the .NET 8 and .NET 9 end-of-support dates mean, why .NET 10 is the logical migration target for many applications, and how to plan an upgrade without introducing unnecessary downtime or business disruption.Key TakeawaysSupport ends in November 2026: Microsoft lists November 10, 2026, as the end-of-support date for .NET 8 and .NET 9. Veri...