Microsoft drops .NET 11 Preview 6 and July servicing updates as .NET 8 and .NET 9 sprint toward end-of-support
Security patches land for the aging platforms, C# unions ship in the preview, and November 10 becomes the critical deadline.
Microsoft released servicing updates for .NET 8.0.29, .NET 9.0.18, and .NET 10.0.10 on July 14, alongside the sixth preview of .NET 11. If you're running .NET 8 or .NET 9, the calendar is getting tight. Both platforms are staring down end-of-support on November 10, 2026. That's roughly four months away.
All three servicing releases patch the same 17 CVEs. You get three critical remote code execution vulnerabilities fixed, alongside elevation of privilege and denial of service fixes. The critical ones involve RCE, so that's the priority. Head here to the .NET 10 release notes to see the full list of patches.
Here's the kicker: November 10, 2026 is the same day .NET 11 is expected to hit RTM. Microsoft is essentially signaling that your current options expire the day the new one arrives. .NET 8 has been supported since November 2023. .NET 9 since November 2024. After November 10, no security updates will flow. Your apps will continue to run, but you'll be flying solo with unpatched vulnerabilities.
.NET 9 received a 24-month STS extension, yet it still collides with .NET 8's end date. The extension happened after the initial date was set, so the collision remains. You can't stretch .NET 9 past the November deadline.
.NET 10: The LTS to target
.NET 10.0.10 ships with SDK versions 10.0.302 and 10.0.110. It's the current LTS and the recommended path for production apps. You need Visual Studio 18.8 for the full experience, though VS Code with the C# Dev Kit works too.
This is the fastest .NET release to date. The JIT compiler sees better inlining and method devirtualization. Intel silicon gets AVX10.2 support. Arm64 devices see SVE vectorization with write-barrier improvements that can reduce GC pauses by 8% to 20%. That's meaningful for high-throughput workloads.
C# 14 brings field-backed properties, extension properties, and null-conditional assignment. F# 10 introduces ValueOption for struct-based optional parameters. Post-quantum cryptography is also here with ML-DSA and ML-KEM support via Windows CNG. If your compliance team is pushing for post-quantum readiness, this is the version to pick up.
.NET 11 Preview 6: Unions ship, MAUI dumps Mono
Preview 6 lands with SDK 11.0.100-preview.6. C# unions are shipping their support types in this release. You can use union patterns now without waiting for RTM. OpenAPI 3.2 is now the default for ASP.NET Core. MAUI is ditching Mono for CoreCLR as the sole runtime for mobile apps. That marks a distinct era change for cross-platform developers.
Microsoft let developers spend hours with the .NET 11 Preview 6 bits, and the C# union support feels like the feature the community asked for years ago. At the time of that preview, Microsoft said it would stabilize the unions before RTM. But in July, the company confirmed they're shipping the support types in this release, meaning you can start using them now without the usual preview caveats.
The Microsoft Agent Framework also makes an appearance, unifying Semantic Kernel and AutoGen. It supports multiple workflow patterns and the AG-UI protocol for human-agent interactions. If you're building multi-agent AI systems, this preview gives you the first class tooling to experiment with.
MAUI gets a significant boost with the CoreCLR transition. Microsoft published a companion timeline detailing the migration from Mono. MAUI mobile apps will use CoreCLR exclusively going forward. You'll see CollectionView2 on Windows, HybridWebView that's AOT-safe, and Android MediaPicker result recovery.
November 10, 2026 is the deadline. You've got about four months to act. Microsoft is pushing hard to get organizations off .NET 8 and .NET 9. You'll have two years left on .NET 10 LTS, which ends November 14, 2028. Visual Studio 2022 will start marking .NET 8 and .NET 9 components as out of support in future servicing updates. The "remove out of support components" option can help clean up your installation.
Keep in mind that .NET 11 Preview 6 requires a standalone runtime installation and is compatible with Visual Studio 18.7 latest preview. Visual Studio for Mac is not supported for these preview releases.
Use GitHub Copilot to help with the migration. The tooling integration is deep, and Copilot can assist with refactoring legacy code to .NET 10 features.
November 10 is the line in the sand. Patch your .NET 8 and .NET 9 apps now, and plan the move to .NET 10 before the clock runs out.
