.NET End of Life - Dates and Lifecycle

.NET covers two different things that share a name but not a support model: the modern, cross-platform .NET runtime (.NET 6, 8, 9, 10, and onward) and the older Windows-only .NET Framework (up through 4.8), which most enterprise Windows applications were built on for over a decade. Knowing which one you're running matters, because their end of life dates, often abbreviated EOL, work completely differently.

.NET Lifecycle Explained

Modern .NET ships a new major version every November, and each release is assigned one of two support tracks at launch. Even-numbered releases, like .NET 6, 8, and 10, get Long Term Support (LTS) for three years from general availability. Odd-numbered releases, like .NET 7 and .NET 9, get Standard Term Support (STS), originally 18 months but extended to 24 months starting with .NET 9, announced in September 2025. That change had a notable side effect: .NET 8 (LTS) and .NET 9 (STS) now both reach end of life on the same day, November 10, 2026, since the extended STS window happened to land on .NET 8's existing LTS end date.

The .NET Framework operates on an entirely different model. Rather than a fixed support window, its lifecycle is tied to the Windows operating system version it ships with. .NET Framework 4.8, for example, has no announced end of life date because it's supported for as long as the underlying Windows release it's bundled with remains supported, which in practice can stretch well beyond the support window of far newer .NET versions. Older .NET Framework releases (like 3.5) have their own separate, extended timelines set by Microsoft's Windows lifecycle policies rather than the annual .NET release cadence.

Regardless of which track a version is on, once it's out of support, Microsoft stops shipping fixes, updates, and online technical assistance for it. Any vulnerability discovered afterward stays unpatched by Microsoft.