Weekly .NET Roundup: .NET 11 Preview 2 and March Servicing

by TechHub

This week’s .NET updates split into new features to try and updates to apply. .NET 11 Preview 2 added runtime, observability, and web/data updates, while .NET 10/9/8 servicing focused on secure, stable builds plus an out-of-band macOS debugger hotfix for VS Code users.

.NET 11 Preview 2: runtime, web, and data stack updates

.NET 11 Preview 2 includes updates that show up in applications and pipelines. Runtime work continues on async improvements (V2) plus JIT/VM changes like cached interface dispatch for interface-heavy hot paths. Libraries also get targeted performance improvements (for example, Matrix4x4.GetDeterminant is ~15% faster) and functional additions like generic GetTypeInfo support in System.Text.Json for source-gen and type-metadata scenarios. SDK changes reduce day-to-day friction: smaller SDK installers on Linux/macOS (useful for development and smaller CI images), improved analyzers, and more warnings/targets to surface issues earlier. Language changes are light for C# and Visual Basic, while F# adds developer-focused updates like overload resolution caching, new preprocessor directives, and new collection functions. ASP.NET Core and Blazor leaned into built-in platform features. Native OpenTelemetry tracing in ASP.NET Core reduces custom tracing setup, OpenAPI 3.2.0 support updates API description workflows, and there’s a new .NET Web Worker template. Blazor adds TempData for state that survives redirects/navigation. EF Core adds server-side translation for LINQ MaxBy/MinBy plus SQL Server features like DiskANN vector indexes and VECTOR_SEARCH(), along with full-text catalogs/indexes and JSON_CONTAINS(). UI and deployment edges also moved forward. .NET MAUI includes Map control and TypedBinding performance work, immutability annotations for Color/Font, and API consistency (notably VisualStateManager), while Windows Forms/WPF get reliability updates. Container teams also get smaller images (SDK images up to ~17% smaller), which improves pulls and CI throughput. Preview 2 is available via the .NET 11 Preview 2 SDK, Visual Studio 2026 Insiders on Windows, or VS Code with C# Dev Kit for early validation and tracking release notes.

Built-in Zstandard compression in .NET 11 and ASP.NET Core

.NET 11 adds built-in Zstandard (zstd) support. System.IO.Compression will include zstd alongside gzip/Deflate and Brotli, which removes the need for third-party wrappers when you want zstd’s compression profile and gives framework components a standard implementation to use. ASP.NET Core also gains zstd as an out-of-the-box HTTP response compression encoding, so teams can evaluate it like gzip or Brotli when balancing payload size vs CPU. The session covers the new APIs for direct use (streams/files) and indirect use (middleware/framework) and includes benchmarks to help decide when zstd fits versus existing algorithms.

.NET servicing: March security patches and a macOS VS Code debugger hotfix

March 2026 servicing shipped clear “update now” guidance for teams on multiple .NET versions. Patched releases are .NET 10.0.4, .NET 9.0.14, and .NET 8.0.25, with installers/binaries, MCR container images, Linux package instructions, and known-issues pages. Security includes three “.NET Security Feature Bypass” CVEs: CVE-2026-26130 (.NET 10/9/8), CVE-2026-26127 (.NET 10/9), and CVE-2026-26131 (.NET 10 only). The practical guidance is to update SDKs/runtimes on developer machines, build agents, deployed hosts, and base images, then validate against the known-issues lists. The roundup also links servicing-approved-issue queries for ASP.NET Core, EF Core, runtime, WPF, and more so you can find fixes that may affect your applications. A second servicing item followed: .NET 10.0.5 out-of-band fixed a macOS-only debugger crash regression introduced in .NET 10.0.4 when debugging from VS Code, especially impacting Apple Silicon (ARM64). If affected, install the .NET 10.0.5 SDK, restart VS Code, and confirm with dotnet --version. If you are not on macOS or are not seeing the crash, the guidance says staying on 10.0.4 is fine because 10.0.5 targets this issue narrowly.

Other .NET News

NetEscapades.EnumGenerators adjusted its package layout to better match how source generators are consumed. The split adds a metapackage for the default path, a Generators-only package for keeping the generator private (for example, PrivateAssets="All"), and a RuntimeDependencies package for option/serialization types that generated code may need. The change addresses missing-type issues when teams exclude runtime assets.