Enterprise teams using .NET 8 or .NET 9 now face a unified migration deadline: November 10, 2026. Both versions reach end-of-support simultaneously due to Microsoft extending Standard Term Support to 24 months. The target is .NET 10 LTS, arriving in November 2025 with support until November 2028.

This creates an unusual situation where both the conservative LTS and feature-focused STS versions expire together. .NET 10 LTS isn't just a stability release; it delivers substantial performance gains—up to 50% faster execution and 60% less memory usage in benchmarks. It also includes built-in post-quantum cryptography and AI-ready infrastructure via the Microsoft Agent Framework.

For developers, migration complexity varies. Moving from .NET 9 is straightforward, often taking days, while leaving .NET 6/7 is a critical security remediation. A key constraint: .NET 10 requires Visual Studio 2026. Developers can start with VS Code today, but enterprises should plan for the new IDE's general availability in early 2026.