State of .NET 2026

.NET 10 shipped on November 11, 2025 as a Long-Term Support release (supported through November 2028). The release included C# 14, F# 10, ASP.NET Core 10 with OpenAPI 3.1 document generation defaults, Blazor 10 with a 76% smaller JavaScript bundle, Entity Framework Core 10 with vector search support, .NET MAUI 10, and .NET Aspire 13.0 adding polyglot orchestration for Python and JavaScript applications.

In early 2026, TIOBE named C# its 2025 Language of the Year for the second time in three years. By November 2025, C# reached 7.65%, up 2.67 points year-over-year, narrowing the gap with Java (8.54%) to 0.89 percentage points. As of January 2026, C# stands at 7.39% versus Java's 8.71%—a gap of 1.32 points.

Microsoft reported over 7 million .NET developers using the Visual Studio family monthly, with over 290,000 pull requests received since open-sourcing and more than 23,000 merged into .NET 10 alone. Other major releases included Visual Studio 2026 (November 11) with AI-integrated workflows, GitHub Copilot integration for testing and modernization, the Microsoft Agent Framework (preview) consolidating Semantic Kernel and AutoGen, and Model Context Protocol C# SDK (preview) with reported production usage in Xbox Gaming Copilot and Copilot Studio.

The security landscape included CVE-2025-55315 (CVSS 9.9, Kestrel request smuggling—one of the highest-scoring ASP.NET Core vulnerabilities) and 23 malicious NuGet packages publicly reported in 2025 (14 crypto-impersonation packages from ReversingLabs, 9 time-delayed destructive packages from Socket) targeting cryptocurrency wallets and industrial control systems. Microsoft extended Short-Term Support releases from 18 to 24 months, creating a November 10, 2026 end-of-support convergence for both .NET 8 and .NET 9. .NET 11 Preview 1 is expected in February 2026.

Security through-line: Monthly Patch Tuesday servicing was punctuated by two defining events: CVE-2025-55315 (Kestrel request smuggling) and a visible rise in NuGet supply chain attacks targeting crypto and industrial control scenarios.

January 14 — Patch Tuesday addressed multiple CVEs: CVE-2025-21171 (.NET Remote Code Execution) and CVE-2025-21173 (.NET Elevation of Privilege on Linux). Microsoft released .NET 8.0.12 and 9.0.1 to address all vulnerabilities. With .NET 8 (released November 2023) as the current LTS, many organizations started 2025 planning migrations off older releases. .NET 6 LTS reached end-of-support on November 12, 2024, and .NET 7 (short-term support) had already gone out of support in May 2024. Community discussion on Reddit's r/dotnet about the fast annual release cadence set the stage for a significant policy change later in the year.

January 29-31 — NDC London 2025 opened the conference season with 27 technical sessions. Scott Hanselman delivered the keynote on .NET innovations, with sessions covering cloud-native development with .NET Aspire and AI integration patterns.

February 11 — Visual Studio 2022 v17.13 shipped with customizable UTF-8 encoding and GitHub Copilot free tier (2,000 completions/month, 50 chat messages). C# Dev Kit for VS Code received preview of solution-free workspace mode, .NET Aspire orchestration from command palette, and experimental Hot Reload support for Razor and Blazor components. .NET 9.0.2 shipped with SDK versions 9.0.103 and 9.0.200.

February 25 — .NET 10 Preview 1 launched with AVX10.2 SIMD support, early C# 14 language features, runtime JIT optimizations, and cryptography improvements. .NET Aspire 9.1 added GitHub Codespaces and Dev Container support, visual resource relationship nesting, advanced filtering by type and state, CORS support, and downloadable console logs.

March 2025 — MVP Summit 2025 brought 120+ MVPs to Microsoft's Redmond campus for NDA-covered technical sessions. Attendees toured The Garage, the Inclusive Tech Lab, and Studio B, while the MVP Authors Event celebrated over 130 books. The gathering coincided with Microsoft's 50th anniversary celebrations on April 4.

March 11 — Patch Tuesday addressed CVE-2025-24070, a high-severity elevation of privilege vulnerability in ASP.NET Core Identity's RefreshSignInAsync method. The flaw allowed attackers to sign into another user's account under certain conditions. Patches arrived in ASP.NET Core 9.0.3 and 8.0.14.

March 18 — .NET 10 Preview 2 landed with Blazor enhancements (updated project template with built-in reconnection UI), .NET MAUI improvements, WinForms-WPF clipboard sharing, and ASP.NET Core refinements (streaming HttpClient responses by default in WebAssembly, new authentication/authorization metrics).

April 8 — Patch Tuesday addressed CVE-2025-26682, a high-severity denial-of-service vulnerability in ASP.NET Core's HTTP/3 implementation allowing resource allocation without limits when using HTTP/3, potentially overwhelming servers under malicious load. Updates released for .NET 9.0.4 and .NET 8.0.15.

April 2025 — .NET 10 Preview 3 shipped with native container publishing for console apps via new dotnet publish options with <ContainerImageFormat> MSBuild property, OpenAPI 3.1 support with improved schema validation, C# 14 extension members allowing developers to augment third-party types, declarative output caching for Blazor and ASP.NET Core, and server-side state preservation options.

April 22-23 — .NET Conf: Focus on Modernization 2025 showcased AI-assisted modernization with the GitHub Copilot Upgrade Tool, migrations from WinForms to Blazor, and the Application and Code Assessment Toolkit (AppCAT) for identifying migration blockers. Scott Hanselman's highlight session posed: "What if AI could upgrade your 20-year-old code?"

May 13 — Patch Tuesday disclosed CVE-2025-26646, a medium-severity spoofing vulnerability in MSBuild's DownloadFile task. Attackers could exploit external control of file names or paths to manipulate downloaded content over networks. .NET 10 Preview 4 arrived with JSON Patch support with System.Text.Json and improved OpenAPI generation. .NET MAUI 9.0.70 (Service Release 7) shipped, ending support for .NET 8 MAUI—requiring all MAUI developers to migrate to .NET 9 or later for continued updates.

May 19-22 — Microsoft Build 2025 delivered 75+ .NET sessions with ".NET + AI = Amazing" as the central theme. Major announcements included Microsoft.Extensions.AI reaching GA with production-ready abstractions for Azure OpenAI, Anthropic, and other AI providers; GitHub Copilot Coding Agent for assigning development tasks directly in GitHub; GitHub Copilot for .NET Upgrade Assist demonstrating weeks of upgrade effort reduced to hours; GitHub Copilot for .NET Aspire with context-aware dashboard integration; .NET Aspire declared production ready after years in preview; single-file program execution with dotnet run <file> without a project; C# 14 language features sneak peek; Copilot "Ask Mode" vs. "Agent Mode" toggle; and Edit CLI editor launch blending MS-DOS Editor nostalgia with VS Code sensibilities. SQL Server 2025 (Preview) announced as an "AI-ready" database with embedded ML model capabilities. The conference concluded with Mark Russinovich and Scott Hanselman connecting Copilot+ PCs, local models, frontier AI services, and robots in a live coding extravaganza with 120+ MVPs and Regional Directors participating.

May 19-23 — NDC Oslo 2025 gathered 2,000+ developers at Oslo Spektrum with sessions on AI integration patterns with .NET, semantic search with Azure OpenAI embeddings, local LLM deployment with Ollama, .NET Aspire 9.3 demonstrations, and legendary community events including The Linebreakers concert and Phil Nash's karaoke session.

May 13 — Visual Studio 2022 v17.14 GA released with Agent Mode preview for multi-step complex coding from natural language, Live Preview for .NET MAUI with real-time UI preview during development, new Mono debug engine integrated into Visual Studio's core debugger, and monthly release cadence going forward.

June 10 — .NET 10 Preview 5 released as the feature-complete build for C# 14, including Post-Quantum Cryptography (PQC) support with experimental Crystals-Kyber (ML-KEM and ML-DSA), OpenAPI 3.1 generation with some APIs marked as experimental, .NET MAUI refinements with bug fixes and XAML global namespace support, and runtime and libraries fine-tuning. .NET 9.0.6 shipped with SDK 9.0.301.

June 19 — dotNET 2025 Madrid held at Kinepolis as the largest .NET event in Europe with 1,000+ attendees.

July 15 — .NET 10 Preview 6 shipped with performance tuning and SDK convenience improvements.

July 29 — .NET Aspire 9.4 released with Aspire CLI reaching GA, interactive dashboard enhancements, visual resource relationship nesting, advanced filtering, CORS support, and downloadable console logs with ANSI color toggle.

August 12 — .NET 10 Preview 7 shipped with AES KeyWrap with Padding (RFC 5649) support and continued runtime and library improvements.

August 26 — .NET Day Switzerland 2025 held community conference in Zürich.

September 9 — .NET 10 Release Candidate 1 released as production-ready. Visual Studio 2026 Insiders launched as a preview channel with Copilot AI deeply integrated, faster C# build/test cycles, and refreshed Fluent UI design.

September 2025 — Microsoft announced significant change to .NET's release support lifecycle: Short-Term Support (STS) releases now receive 24 months of support instead of 18 months, effective retroactively starting with .NET 9. .NET 9's end-of-support extended to November 10, 2026. Notably, both .NET 8 and .NET 9 will reach end of support on the same day—November 10, 2026—creating a unified migration target for enterprises. .NET Aspire 9.5 released with Generative AI Visualizer for inspecting LLM prompts, token usage, costs, model responses, and tool invocation chains; and single-file AppHost.

October 8-9 — JetBrains .NET Days Online 2025 held free virtual event covering Aspire, Blazor, and ASP.NET MVC.

October 14 — Patch Tuesday disclosed CVE-2025-55315, a critical CVSS 9.9 HTTP Request Smuggling vulnerability in ASP.NET Core Kestrel. The vulnerability allowed attackers to craft ambiguous HTTP requests by manipulating Content-Length and Transfer-Encoding headers, enabling request smuggling that could bypass authentication mechanisms, evade WAF rules, access unauthorized endpoints, and poison web caches. Affected supported ASP.NET Core versions 8, 9, 10 (pre-rc2), plus ASP.NET Core 2.x (2.3). CVE-2025-55247 (denial of service via predictable MSBuild temp directories on Linux) and CVE-2025-55248 (MITM TLS downgrade in SMTP connections) also disclosed. .NET 10 Release Candidate 2 released with final validation before GA. Microsoft formalized the .NET Security Group, expanding the coalition with Red Hat, IBM, and Canonical for coordinated vulnerability response that had existed privately since 2016.

October-November — Security firm Socket disclosed nine malicious NuGet packages with time-delayed payloads. Sharp7Extend and similar packages targeted Siemens S7 PLC industrial controllers, silently corrupting 80% of write operations after running for 30+ minutes, with one package randomly killing the host process 20% of the time starting on a trigger date in 2027. These attacks achieved ~9,500 combined downloads before removal.

November 10 — DNF Summit 2025 held .NET Foundation community gathering.

November 11 — .NET 10 GA released as LTS version supported through November 2028, including C# 14 with the field keyword, extension members, null-conditional assignment (?.=), implicit Span<T> conversions, and user-defined checked operators; F# 10 with scoped warning suppression, access modifiers on auto property accessors, ValueOption optional parameters, tail-call support in computation expressions, and unified Span<T> support; ASP.NET Core 10 with OpenAPI 3.1 by default with YAML serving, built-in validation for Minimal APIs via AddValidation(), WebAuthn/FIDO2 passkey support, native Server-Sent Events support, automatic memory pool eviction, and Kestrel security hardening following the request smuggling vulnerability; Blazor 10 with 76% smaller JavaScript bundle (blazor.web.js from 183KB to 43KB), circuit state persistence with Blazor.pause(), Hot Reload enabled by default for WebAssembly Debug builds, declarative state persistence via [PersistentState] attribute, new ReconnectionHandler and script compression, and production-ready AOT improvements; Entity Framework Core 10 with production-ready vector search using native vector type and VECTOR_DISTANCE() for AI workloads, native json type for SQL Server 2025, first-class LINQ LeftJoin/RightJoin operators, named query filters with selective disabling, Cosmos DB full-text search functions, Complex Types support for value objects enabling cleaner Domain-Driven Design, and ExecuteUpdate for JSON; .NET MAUI 10 with new default handlers for CollectionView and CarouselView on iOS/Mac Catalyst, Android API 36 targeting with iOS 18.2/Mac Catalyst 18.2 support, HybridWebView enhancements with JavaScript-to-.NET exception forwarding, MediaPicker multi-file selection, new XAML source generator, and experimental CoreCLR runtime for Android dramatically improving performance and stability; and .NET Aspire 13.0 GA with polyglot orchestration for Python and JavaScript applications, modular extensible integrations, simplified AppHost SDK, and agent cluster modeling with full OpenTelemetry observability.

November 11 — Visual Studio 2026 GA released as "world's first Intelligent Developer Environment" with significantly faster large .NET solution load times, UI freezes reduced by more than half, modern Fluent UI design system, full compatibility with Visual Studio 2022 projects and 4,000+ extensions, deep AI integration with GitHub Copilot Profiler Agent analyzing .NET counters, context-aware debugging with Exception Helper providing variable analysis and code inspection, Adaptive Paste adjusting code to match project conventions, All-in-One Search with Did You Mean unifying search across code/settings/docs, improved Hot Reload and Razor editing experiences, GitHub Copilot app modernization for .NET 10 upgrades, and platform requirements requiring 64-bit Windows 10 or Windows 11.

November 11-13 — .NET Conf 2025 celebrated its 15th anniversary and .NET 10 launch. Microsoft highlighted community scale: since open-sourcing, .NET has received over 290,000 PRs, with more than 23,000 pull requests merged into .NET 10 alone. Production use cases: Bing running .NET 10 RCs in production achieving notable latency improvements, Xbox Gaming Copilot running entirely on .NET 10 with Orleans and Aspire, Build conference Copilot Studio app built in Blazor WebAssembly using .NET 10. Partner ecosystem: Red Hat/Canonical/IBM collaborating on secure Linux packages, Syncfusion and Uno Platform contributing to MAUI control ecosystem, AMD and Intel contributing hardware intrinsics for AI/ML performance, Samsung working on RISC-V and ARM64 support. Major announcements included GitHub Copilot App Modernization (GA) with customer FMG upgrading apps "in just hours" instead of weeks; GitHub Copilot Testing for .NET (Preview) with AI-generated unit tests and edge case coverage; Microsoft Agent Framework for .NET (Preview) building intelligent AI agents for autonomous decision-making, unifying Semantic Kernel and AutoGen projects with orchestration patterns, state management, and full MCP support; MCP C# SDK (Preview) already in production for Xbox Gaming Copilot and Copilot Studio; and .NET Aspire 13.0 GA integrating with popular tools. Azure integration: Azure Functions v5 planned for 2026 will run on .NET 10 by default, Azure App Service had day-one support, container images available in MCR registry on launch day. Day 2 focused on Azure and cloud-native scenarios. Day 3 was Community Day with fintech company migrating 100+ apps from .NET Framework 4.8 to .NET 10 in months, Unity game leveraging .NET 6 exploring future .NET 8 adoption, and localized content for China.

November 11 — JetBrains Rider 2025.3 released with day-one .NET 10 and C# 14 support, new Islands theme, F# 10 support, and startup performance improvements.

November 18-21 — Microsoft Ignite 2025 gathered 20,000 professionals in San Francisco for major Azure AI and Microsoft 365 Copilot announcements, with MVPs providing expert insights and priority keynote seating.

November 24 — .NET MAUI 10.0.11 (SR1.1) shipped addressing Shell title clipping, TimePicker crashes, and iOS TitleView issues, following .NET MAUI 10.0.10 (SR1) on November 11 with 100 commits fixing CarouselView2 issues on iOS, IndicatorView interactivity bugs, and app responsiveness problems.

December 9 — .NET December 2025 Updates shipped servicing releases for .NET 8.0.22, 9.0.11, and 10.0.1 as Microsoft's monthly Patch Tuesday addressed 57 CVEs across its portfolio. No new security advisories needed specifically for .NET. SQL Server 2025 continued progressing through preview milestones, with Release Candidate 0 (RC0) announced in August featuring AI-powered capabilities and native JSON type support completing the data platform story for EF Core 10's new features.

December 17 — ReversingLabs published analysis of 14 malicious NuGet packages discovered during October 2025, impersonating cryptocurrency tools (e.g., Nethereum) and designed to steal wallet information and OAuth tokens via typosquatting/homoglyphs, version baiting, and inflated download counts.

December 2025 — JetBrains Rider 2025.3.1 shipped with Next Edit Suggestions (AI-powered file-wide edit recommendations), Claude agent integration, and security fixes for CVE-2025-64456 and CVE-2025-64457. Microsoft planned to phase out .NET 6 and .NET 7 SDK support in C# Dev Kit for VS Code starting January 2026, officially completing the sunset of those versions in the development toolchain. Official .NET Blog published "Top .NET Blog Posts of 2025" highlighting launch of .NET 10, wealth of performance improvements, infusion of AI in .NET workflows (Agent Framework, MCP, Copilot integrations), important security announcements (STS support extension, .NET Security Group), and community contributions. .NET MAUI 10.0.1 updated templates with new .NET MAUI Community Toolkit package versions.

On December 10, 2025, Microsoft disclosed CVE-2025-55315, a critical HTTP Request Smuggling vulnerability in ASP.NET Core Kestrel with a CVSS score of 9.9—one of the highest-scoring vulnerabilities in ASP.NET Core history. The vulnerability allowed attackers to exploit discrepancies in how HTTP/1.1 proxies and Kestrel parsed chunked transfer encoding, enabling a crafted request to be interpreted as two separate requests where the second appeared to come from an authenticated client. Affected versions spanned ASP.NET Core 8, 9, and 10 (pre-rc2), forcing immediate emergency patching across global .NET infrastructure. Microsoft released patches (8.0.21, 9.0.10, 10.0.0-rc2) enforcing stricter HTTP/1.1 parsing rules, detailed mitigation guidance, and paid the researcher a $10,000 bug bounty. The event highlighted the fragility of HTTP parsing in complex microservice architectures and spurred security hardening updates throughout late 2025.

The NuGet supply chain saw escalation from typosquatting to credible operational threats in 2025. Security researchers identified 14 malicious packages impersonating cryptocurrency tooling (e.g., Nethereum) using typosquatting, homoglyphs, and fake version bumps to exfiltrate wallet credentials and OAuth tokens. Security firm Socket disclosed nine malicious packages containing time-delayed logic bombs targeting industrial control systems—packages like Sharp7Extend would silently corrupt 80% of write operations after 30+ minutes of runtime, with one randomly killing the host process 20% of the time starting on a trigger date in 2027. These packages accumulated approximately 9,500 combined downloads before removal, demonstrating that NuGet attacks had evolved from opportunistic theft to sophisticated sabotage targeting industrial infrastructure.

In response to escalating threats, Microsoft formalized the .NET Security Group in October 2025. The coalition had existed privately since 2016 with members like Red Hat, IBM, and Canonical, but was expanded and publicized to coordinate vulnerability disclosure and patch delivery across the ecosystem. When CVE-2025-55315 was fixed, Red Hat's RHEL package, Canonical's Ubuntu package, and Amazon's AWS .NET runtime could all release patches simultaneously with Microsoft, significantly reducing the attack window. The community established new security baselines: aggressive patch cycles (48-hour deployment windows), mandatory dependency scanning using dotnet nuget verify and services like Socket or Snyk, SBOM generation for compliance, and post-quantum readiness experiments with the experimental ML-DSA and ML-KEM APIs introduced in .NET 10 implementing FIPS 203 and FIPS 204 standards.

In October 2025, Microsoft unveiled the Microsoft Agent Framework (preview), consolidating two previously fragmented orchestration libraries—Semantic Kernel and AutoGen—into a unified platform for single-agent orchestration and multi-agent collaboration. Before the Agent Framework, .NET developers faced confusing overlap between Semantic Kernel (Microsoft's LLM orchestration library) and AutoGen (multi-agent framework from Microsoft Research) with incompatible APIs and no clear guidance on selection criteria. The unified framework provides a single API surface supporting OpenAI, Azure OpenAI, Anthropic Claude, Ollama, and other providers with native integration into .NET Aspire for cloud-native AI deployment, ending months of community confusion about library investment decisions.

In November 2025, Microsoft released the Model Context Protocol (MCP) C# SDK in preview, implementing Anthropic's standardized protocol for LLM interaction with external data sources and tools. Despite preview status, Microsoft reported production usage in Xbox Gaming Copilot and Copilot Studio, demonstrating confidence in SDK stability. The SDK provides server and client implementations, resource providers for file systems and databases, and standardized tool calling, integrating seamlessly with the Agent Framework. .NET Aspire 13.0 shipped with GitHub Models integration (preview), Azure AI Foundry integration (preview), ExternalService resources for modeling external URLs, and a Generative AI Visualizer for inspecting LLM interactions, completing the cloud-native AI stack.

The Agent Framework integration gave ML.NET renewed relevance as the "execution engine" for local models within .NET applications, carving out a niche for on-device inference where introducing Python dependencies is architecturally undesirable, production deployment in enterprise .NET applications, edge computing scenarios requiring lightweight runtimes, and cost optimization by avoiding per-token API charges for simple models. Visual Studio 2026 shipped with AI-integrated workflows including Copilot "Ask Mode" versus "Agent Mode" for multi-step autonomous refactoring, agentic debugging inspecting variable states across stack frames, Adaptive Paste adjusting code to project conventions, and GitHub Copilot App Modernization (GA) automating .NET Framework to .NET 10 upgrades—a fintech customer reportedly migrated 100+ apps "in just hours" instead of weeks. While Python maintains dominance in AI research and most papers provide Python implementations, .NET provided a complete stack for deploying AI in production environments without architectural compromises.

.NET 10's runtime incorporated architectural improvements for modern hardware: AVX10 support for Intel processors enabling 256-bit and 512-bit vector operations dynamically, ARM64 SVE (Scalable Vector Extension) for server-class ARM chips with variable-length vector operations, enhanced struct promotion allowing more stack allocations reducing memory traffic overhead, better register allocation, and garbage collection improvements delivering 8-20% reduction in pause times for server applications. C# 14 shipped with the field keyword for semi-auto-properties eliminating backing field boilerplate, extension members expanding to properties and events on types, null-conditional assignment (?.=) simplifying guard clauses, and implicit Span<T> conversions reducing explicit type conversions. These features emphasized developer productivity without sacrificing performance or safety, manifesting as measurable gains in production workloads processing high throughput, particularly for AI inference workloads on CPUs where vector throughput correlates to token generation speed.

Native Ahead-of-Time (AOT) compilation became viable for console apps and microservices, delivering reduced startup time critical for AWS Lambda and Azure Functions cold starts, 50% smaller binary footprint compared to .NET 7 AOT, up to 6x performance gains in micro-benchmarks, and higher container density enabling lower cloud costs and carbon footprint through reduced wattage per request. .NET 10 made containerization first-class with native container publishing (dotnet publish --os linux --arch x64 /t:PublishContainer), new <ContainerImageFormat> MSBuild property for Docker vs OCI formats, and day-one Azure support across App Service, Functions, and Container Apps with images immediately available in Microsoft Container Registry.

The migration from .NET 8 (LTS) to .NET 10 (LTS) was characterized as "smooth but strict"—approximately 90% of projects required only a target framework bump, while teams faced challenges with removed APIs (System.Linq.Async replaced by core libraries, BinaryFormatter excised), stricter globalization in SQLite, and OpenAPI transformer pattern deprecation (ASPDEPR002). Real-world adoption validated the platform: the s&box development team (Garry's Mod successor) migrated to .NET 10 and C# 14 citing measurable performance improvements and runtime stability for performance-critical gaming, a fintech company shared at .NET Conf migrating 100+ apps from .NET Framework 4.8 to .NET 10 in months using GitHub Copilot and AppCAT, and Unity Technologies shared plans to move from Mono 2018 to .NET 8 LTS by end of 2025 citing huge performance and tooling gains.

ASP.NET Core 10 shipped with OpenAPI 3.1 document generation enabled by default for all Web API projects with built-in validation and schema customization, native Server-Sent Events (SSE) support through IAsyncEnumerable<T> eliminating third-party libraries, and built-in WebAuthn/FIDO2 support for passwordless authentication with passkeys. Blazor 10 delivered a 76% smaller JavaScript bundle (183KB to 43KB) through aggressive dead code elimination and WebAssembly optimization, circuit state persistence across reconnections improving mobile experience with Blazor.pause() API and [PersistentState] attribute, and HybridWebView enhancements for richer MAUI integration with shared code. These improvements dramatically reduced initial page load times, especially on mobile networks, while improving resilience for unstable connections—Hot Reload became enabled by default for WebAssembly Debug builds matching the Blazor Server developer experience.

Entity Framework Core 10 added native vector similarity search support in SQL Server and PostgreSQL with native vector type and VECTOR_DISTANCE() function enabling semantic search, recommendation engines, and RAG (Retrieval-Augmented Generation) patterns without external vector databases, JSON columns as default storage for complex object hierarchies reducing manual flattening (breaking existing schemas expecting nvarchar(max)), and direct LeftJoin and RightJoin query operators improving SQL translation for complex queries. .NET Aspire 13.0 shipped with polyglot orchestration supporting Python and JavaScript applications alongside .NET services, Aspire CLI graduating to general availability for production-ready deployment automation with aspire new, aspire add, aspire run, and aspire config commands, and the team's first transparent six-month public roadmap showing planned Azure integrations and breaking change timelines.

The platform matured through ecosystem stability improvements: third-party libraries like IronPDF and IronXL confirmed immediate .NET 10 support, logging frameworks (Serilog, NLog) announced RC1 compatibility, while older reporting libraries and vendors like ComponentOne and Telerik created enterprise migration bottlenecks requiring months for certification. The community established migration best practices: audit dependencies using dotnet list package --vulnerable and --outdated, test in isolated branches, enable .NET upgrade assistant and Roslyn analyzers, deploy incrementally to non-production environments first, monitor with Application Insights or OpenTelemetry for regressions, and maintain .NET 8 builds during transition periods for rollback capability. Microsoft extended Short-Term Support releases from 18 to 24 months, creating a November 10, 2026 end-of-support convergence for both .NET 8 and .NET 9.

When: February 2026 (expected) Context: .NET 11 previews typically begin 3-4 months after the LTS release. As a Standard Term Support (STS) release, it will receive 2 years of support (extended from 18 months thanks to September 2025 policy change). Expected themes include Agentic UI (AG-UI initiative where UI components are agent-aware), Distributed Reliability (baking resilience patterns deeper into HttpClient and networking stack), Green Computing (optimizing for energy efficiency), and performance refinement. First Preview around February with early bits of C# 15, monthly previews throughout 2026, and clearer picture of feature set by Build 2026. Action: Monitor preview releases for experimental features. Test .NET 10 LTS in production while evaluating .NET 11 preview features for future planning. Preview cycle informed by .NET 10 production feedback.

When: November 10, 2026 Context: Microsoft's support timeline change means both .NET 8 LTS and .NET 9 STS reach end-of-support on the same day, creating a unified migration target. Organizations must migrate to .NET 10 by this date to maintain support. .NET 10 supported until November 2028. Organizations running .NET 8 LTS have two choices: (1) Jump to .NET 10 LTS during 2026 for three years of support, or (2) Bridge with .NET 11 (STS) then move to .NET 12 LTS in 2027. Microsoft's extended 24-month STS policy makes option 2 more viable than before. Action: Begin migration planning immediately. Use GitHub Copilot App Modernization tools to assess upgrade blockers. Allocate Q3-Q4 2026 for testing and deployment to .NET 10.

When: Throughout 2026 Context: Visual Studio 2026 shipped as the "First Intelligent Developer Environment" with deep AI integration. Expect monthly releases to add Agent Mode capabilities, expanded Copilot features, improved AI-assisted debugging, and extension ecosystem migration from VS 2022. Visual Studio Code will continue receiving C# Dev Kit updates, with .NET 6/7 SDK support planned to be phased out starting January 2026 marking the end of those versions in the development toolchain. Expected: AI agent integration patterns stabilizing, MCP server availability for development tasks, monthly updates bringing new AI model support, continued performance improvements, and extension marketplace modernization. Action: Adopt Visual Studio 2026 for new projects. Explore Agent Mode for complex refactoring tasks. Provide feedback to shape AI-native development workflows.

When: H1 2026 Context: MCP C# SDK reached preview in November 2025 and is already in production for Xbox Gaming Copilot and Copilot Studio. Expect GA release and rapid ecosystem expansion with community-built MCP servers for databases, APIs, and custom tools. The Agent Framework, MCP C# SDK, and GitHub Copilot integrations announced at .NET Conf 2025 will mature throughout 2026 with Agent Framework GA releasing as production-ready (Microsoft.Agents.AI), tighter IDE integration with more autonomous refactoring, expanded agent capabilities with better tool discovery and state management, production deployment patterns with established best practices, and growing MCP server ecosystem library of reusable tool integrations. Action: Build MCP servers for internal tools and data sources. Integrate MCP into AI agent architectures. Monitor MCP registry for reusable community servers.

When: Q1-Q2 2026 (GA expected) Context: The Agent Framework preview unified Semantic Kernel and AutoGen, providing production-ready primitives for autonomous AI agents. GA release will signal readiness for enterprise adoption with orchestration patterns and state management. Action: Prototype agentic workflows with preview builds. Plan migration from Semantic Kernel or AutoGen to unified Agent Framework. Design multi-agent systems for complex automation scenarios.

When: 2026-2027 Context: .NET 10 introduced experimental support for ML-DSA (Digital Signature) and ML-KEM (Key Encapsulation) based on CRYSTALS-Kyber. As quantum computing advances, organizations must prepare for quantum-resistant cryptography. Action: Begin experimenting with post-quantum algorithms in non-production environments. Identify systems requiring long-term cryptographic security. Plan phased migration to quantum-resistant algorithms as they mature and standardize.

When: Throughout 2026 Context: .NET MAUI faced persistent quality debates in 2025, with some developers abandoning the platform following the viral "Why I Don't Use .NET MAUI Anymore" article. 2026 is critical for proving sustained quality improvements, competitive performance with Flutter/React Native, and enterprise adoption beyond pilot projects. Potential developments: MAUI on Linux via community efforts (Uno Platform aiding), expanded Skia or web backends, and if matured, truly cross-platform across Win/macOS/Linux. Unity's move to .NET Core in 2026 could provide positive spillover effect for MAUI adoption in game tooling. Action: Evaluate .NET MAUI 10 for cross-platform projects with caution. Monitor service releases (SR2, SR3) for stability improvements. Consider Uno Platform or Avalonia as alternatives if MAUI quality concerns persist.

When: Throughout 2026 Context: Blazor 10 delivered 76% smaller JavaScript bundles and improved AOT support. Expect continued optimization in 2026 with better trimming, faster startup times, and enhanced interop performance, making Blazor increasingly competitive with JavaScript frameworks. Action: Migrate Blazor WebAssembly apps to .NET 10 for bundle size improvements. Enable AOT compilation for production workloads. Profile startup performance and leverage new optimization features as they ship.

When: Q1-Q2 2026 Context: EF Core 10 introduced production-ready vector search with native vector type and VECTOR_DISTANCE() for AI workloads. Combined with SQL Server 2025's native JSON type, this enables sophisticated AI application data architectures. EF Core 11 expected with expanded vector database integrations (Pinecone, Weaviate, etc.), improved semantic search patterns, RAG (Retrieval-Augmented Generation) application frameworks, better LINQ support for vector distance queries, and integration with AI agent memory stores. Action: Implement vector search for semantic search, recommendation engines, and RAG (Retrieval-Augmented Generation) systems. Upgrade to SQL Server 2025 to leverage native JSON and vector capabilities. Profile vector search performance against dedicated vector databases.

When: Throughout 2026 Context: Aspire 13.0 GA introduced polyglot orchestration for Python and JavaScript applications, positioning .NET as the orchestration layer for heterogeneous microservice architectures. Expect enhanced integrations and broader language support, deeper integration with non-.NET workloads, expanded Azure and AWS integrations, continued CLI improvements, enhanced dashboard AI visualization capabilities, and standardized patterns for agent cluster orchestration. The public roadmap promises continued evolution with community input shaping priorities. Action: Use Aspire for multi-language microservice orchestration. Leverage Aspire dashboard for unified observability across .NET, Python, and JavaScript services. Contribute to Aspire community integrations for additional runtimes and tools.

When: 2026 Context: Azure Functions v5 planned for 2026 will run on .NET 10 by default, bringing LTS stability to serverless workloads. Expect improved cold start performance, enhanced local development experience, and deeper Aspire integration. Action: Plan migration from Azure Functions v4 (.NET 6/8) to v5 (.NET 10). Test isolated worker model for better performance and flexibility. Evaluate Aspire for local serverless development and testing.

When: 2026 Context: C# rose 2.67 percentage points year-over-year by November 2025, with Java at 8.54% and C# at 7.65% (gap of 0.89 percentage points). By January 2026, C# had risen to 7.39% (+2.94 YoY), with Java at 8.71% (gap of 1.32 points). TIOBE CEO noted C# has removed every reason not to choose it over Java, with equal shares in all terrains except finance. 2026 could see the historic crossover as the gap continues to narrow. Action: Position .NET for enterprise adoption in traditionally Java-dominated spaces. Highlight cross-platform capabilities, open-source ecosystem, and AI-native development. Monitor TIOBE Index quarterly for historic crossover milestone.

When: Throughout 2026 Context: The .NET Security Group formalized in October 2025 with Red Hat, IBM, and Canonical enables coordinated vulnerability response. Expect membership expansion (potentially AWS, Alibaba) and more frequent security rollups if needed. Security best practices from 2025 incidents include aggressive patch cycles (48-hour deployment windows), dependency scanning, SBOM generation, NuGet additional verification features (mandatory 2FA, package signing enforcement), and SBOM generation features in build system for regulatory compliance. Action: Maintain aggressive patch cycles with 48-hour deployment windows. Leverage .NET Security Group coordination for simultaneous patches across distributions. Generate SBOMs for compliance and supply chain visibility.

When: Q2-Q3 2026 (GA expected) Context: GitHub Copilot Testing for .NET reached preview in November 2025, enabling AI-generated unit tests with edge case coverage. GA release will integrate seamlessly into Visual Studio 2026 and VS Code workflows. Action: Adopt Copilot Testing for new features to improve test coverage. Review and refine AI-generated tests for accuracy. Measure impact on code quality and bug detection rates.

When: Throughout 2026 Context: Unity's move to .NET Core in 2026 brings millions of game developers to modern .NET and C#. This could provide positive spillover effects for MAUI adoption in game tooling and broader .NET ecosystem growth. Action: Monitor Unity's .NET Core adoption for patterns and best practices. Explore .NET MAUI for game development tools if Unity migration succeeds. Engage with game development community to promote .NET capabilities.

When: Throughout 2026 (.NET 11 previews) Context: .NET 10 set a high bar with AVX10 support and struct promotion optimizations. 2026 will bring continued performance innovation with AVX-512 leveraging, ARM Scalable Vector Extensio