Use C# unions and closed hierarchies in ASP.NET Core
<p>Learn how C# unions and closed hierarchies work with System.Text.Json across ASP.NET Core Minimal APIs, MVC, SignalR, Blazor, and OpenAPI.</p> <p>The post <a href="https://devblogs.microsoft.com/dotnet/unions-and-closed-hierarchies-in-aspnetcore/">Use C# unions and closed hierarchies in ASP.NET Core</a> appeared first on <a href="https://devblogs.microsoft.com/dotnet">.NET Blog</a>.</p>
Announcing .NET 11 Release Candidate 1
<p>.NET 11 Release Candidate 1 is available with improvements across libraries, runtime, SDK, MSBuild, NuGet, C#, F#, ASP.NET Core, .NET MAUI, and Windows Forms.</p> <p>The post <a href="https://devblogs.microsoft.com/dotnet/dotnet-11-rc-1/">Announcing .NET 11 Release Candidate 1</a> appeared first on <a href="https://devblogs.microsoft.com/dotnet">.NET Blog</a>.</p>
.NET Conf 2026 Community Days Call for Presenters Is Open
<p>Submit your session proposal for the community-led .NET Conf 2026 Community Days by October 6, 2026.</p> <p>The post <a href="https://devblogs.microsoft.com/dotnet/dotnet-conf-2026-community-days-call-for-presenters/">.NET Conf 2026 Community Days Call for Presenters Is Open</a> appeared first on <a href="https://devblogs.microsoft.com/dotnet">.NET Blog</a>.</p>
.NET and .NET Framework September 2026 servicing releases updates
<p>A recap of the latest servicing updates for .NET and .NET Framework for September 2026.</p> <p>The post <a href="https://devblogs.microsoft.com/dotnet/dotnet-and-dotnet-framework-september-2026-servicing-updates/">.NET and .NET Framework September 2026 servicing releases updates</a> appeared first on <a href="https://devblogs.microsoft.com/dotnet">.NET Blog</a>.</p>
GPT-6 Astra for .NET: What Changes in the API, and Where the SDK Hasn't Caught Up
OpenAI shipped GPT-6 Astra on September 3, 2026. Before wiring it into a .NET project, here's the actual API contract — context window, pricing, reasoning effort — checked against the live docs, plus what I found installing the real OpenAI NuGet package: the stable client can't do Astra's tool calling at all, the client that can is still experimental, and the SDK's named reasoning levels stop short of what the model documents.
GPT-6 Astra in .NET
Stable Chat Completions, the Microsoft.Extensions.AI bridge, and the still-experimental Responses API against GPT-6 Astra, side by side behind one CLI arg each. Companion repo for the article.
The Coffee Timer
A Pomodoro-style focus timer with task tracking, visual themes, and premium features like Spotify playback and a productivity calendar. Backend on .NET with Supabase, subscription checks handled server-side.
Test what you ship: MSTest and Native AOT
<p>MSTest source generation lets test projects use the same Native AOT and trimming deployment model as the applications they validate, while reducing reflection on the test execution path.</p> <p>The post <a href="https://devblogs.microsoft.com/dotnet/mstest-source-generation/">Test what you ship: MSTest and Native AOT</a> appeared first on <a href="https://devblogs.microsoft.com/dotnet">.NET Blog</a>.</p>