Microsoft has confirmed that both .NET 8 (LTS) and .NET 9 (STS) will reach end of support on November 10, 2026, a rare simultaneous termination that breaks the traditional LTS support window. This means applications still running on these versions will no longer receive security patches or critical updates, exposing organizations to vulnerabilities and compliance hurdles. The official recommendation is to upgrade to .NET 10 LTS, which is supported until 2028. This move reflects Microsoft's strategy of faster release cycles, but it also reduces the predictability of LTS longevity that enterprise teams rely on. For development teams, this is a clear signal to audit their .NET version inventory, plan migration sprints, and test compatibility with .NET 10 well before the deadline. Ignoring the countdown could lead to unpatched systems, failed audits, and increased operational risk. The .NET ecosystem is evolving rapidly, and staying current is no longer optional—it's a business necessity.
Microsoft ends support for .NET 8 and .NET 9 simultaneously on November 10, 2026, breaking LTS promises. Upgrade to .NET 10 LTS is strongly advised to avoid security and compliance risks.