The .NET Insider – Issue 20

.NET 11 Preview 2 is now available and brings the latest improvements across the .NET runtime, SDK, libraries, ASP.NET Core, Blazor, .NET MAUI, and related tooling. As part of the ongoing preview cycle, the release focuses on performance improvements, developer productivity, and enhancements to the overall .NET ecosystem. Developers can experiment with the new SDK to explore upcoming features, test compatibility, and provide feedback before the final release. The preview also continues the platform’s investment in cloud-native development, container support, and modern application scenarios. With each preview release, Microsoft encourages developers to try the new features, review release notes, and help shape the final version of .NET 11 through community feedback and real-world testing.

Microsoft released the March 2026 servicing updates for .NET and .NET Framework, delivering the latest security and reliability fixes across supported versions of the platform. These monthly updates include patches for security vulnerabilities as well as improvements to stability and performance. Developers and organizations running production workloads are encouraged to install these updates to ensure their applications remain secure and fully supported. The release covers several supported .NET versions and provides details about resolved issues and addressed CVEs. As part of Microsoft’s regular servicing cycle, these updates help maintain the health and security of applications built on the .NET ecosystem while ensuring compatibility with modern operating systems and cloud environments.

The .NET team introduced .NET Skills, a new approach to enhancing coding agents with reusable capabilities tailored for .NET development. The post explains how developers can extend AI coding agents by providing specialized skills that supply additional context, commands, and workflows relevant to .NET projects. These skills help agents better understand tasks such as working with project structures, running CLI commands, generating code, or interacting with development tools. The goal is to make AI agents more effective collaborators by giving them structured knowledge about the .NET ecosystem. The article also introduces the open-source dotnet/skills repository, which serves as a starting point for developers who want to create, share, and reuse skills across AI-powered development workflows.

Modernizing legacy .NET applications can be challenging, but GitHub Copilot is increasingly being used to accelerate the process. This post introduces a modernization approach powered by Copilot that follows an assess → plan → execute workflow. Developers can analyze existing applications, generate modernization plans, and implement improvements using AI-assisted tooling. The approach works across multiple environments including Visual Studio, Visual Studio Code, GitHub Copilot CLI, and GitHub itself. By combining AI-assisted analysis with developer expertise, teams can gradually update older applications to modern .NET versions, improve architecture, and adopt cloud-native patterns. The post highlights how Copilot can reduce repetitive work and help teams modernize large codebases more efficiently.

This article demonstrates how modern AI development tools can work together by building a real-world application using Microsoft Agent Framework, Microsoft Foundry, Model Context Protocol (MCP), and .NET Aspire. The example project—an Interview Coach application—illustrates how developers can design intelligent systems that coordinate multiple AI capabilities while maintaining scalable architecture. The post walks through how these technologies integrate to support agent-based workflows, cloud-native deployment, and interoperability between services. It also highlights how Aspire helps orchestrate services and infrastructure while MCP enables standardized communication between AI tools and external systems. The result is a practical blueprint for developers who want to build advanced AI-driven applications using the modern Microsoft ecosystem.

GitHub Copilot CLI brings AI assistance directly into the terminal, enabling developers to review code, generate tests, debug issues, and automate workflows without leaving the command line. This post introduces a free, open-source course designed to help developers learn Copilot CLI step by step. The course consists of eight hands-on chapters that guide learners from installation to building practical AI-powered terminal workflows. Developers can explore how Copilot CLI integrates with everyday tools and how it can be used to create custom agents and reusable skills. The course works with GitHub Copilot Free and can be completed using local environments or GitHub Codespaces. It’s designed to help developers quickly move from experimentation to real productivity with AI-assisted development directly in the terminal.

Visual Studio Dev Essentials is a program that provides developers with free access to a wide range of tools, services, and learning resources from Microsoft and its partners. This post highlights how developers can benefit from the program by accessing tools such as Visual Studio Community, Visual Studio Code, Azure services, and other development utilities. Members also receive free Azure credits, training resources, and access to partner offers that support various stages of the development lifecycle. Whether developers are building cloud applications, learning new technologies, or experimenting with modern tooling, Dev Essentials offers a convenient way to get started without upfront cost. The program is designed to help developers accelerate their projects while gaining access to practical tools and resources used across the Microsoft developer ecosystem.

Windows Terminal Preview 1.25 introduces several improvements aimed at enhancing the developer experience and customization capabilities of the terminal. This release includes updates to the Settings UI, improvements to search functionality within settings, and new features that help users better manage and configure their terminal environments. Additional enhancements improve command palette behavior and provide better support for extensions and localization scenarios. These updates continue Microsoft’s effort to make Windows Terminal a modern, customizable hub for development workflows across Windows environments. For developers who rely heavily on command-line tools, the new preview release brings incremental usability improvements while maintaining the flexibility and performance that Windows Terminal is known for.

In modular monolith architectures, working with multiple database schemas can introduce complexity when queries or transactions span multiple modules. This article explores strategies for safely querying data and executing transactions across schemas while maintaining proper boundaries between modules. Instead of tightly coupling modules through shared database access, the post recommends clear communication patterns such as application services or APIs between modules. It also discusses techniques for coordinating transactions when multiple modules must participate in the same business operation. By following these practices, developers can maintain modularity and avoid turning a modular monolith into a tightly coupled system while still enabling complex workflows that require data from multiple domains.

Domain models play a critical role in how business logic is structured in an application. This article compares two common approaches: anemic models and rich domain models. Anemic models primarily store data and rely on services to implement business logic, while rich models encapsulate both data and behavior within domain entities. The post discusses the trade-offs between these approaches and how they affect maintainability, testability, and domain complexity. While anemic models can be simpler and easier to start with, richer models help enforce business rules and maintain domain integrity as applications grow. The article provides guidance on when each approach may be appropriate and how developers can gradually evolve their domain model as business requirements become more complex.