On June 11, 2025, Microsoft released .NET 10 Preview 5, bringing some interesting improvements to the .NET ecosystem. This release is part of the journey toward the official .NET 10 launch (November 2025), with a focus on optimizations for developers, performance, and a modern experience.
In this article, we will review the most important news.
🧠 1. Dynamic AOT for ASP.NET Core
One of the most interesting announcements is the experimental support for Dynamic AOT (Ahead-of-Time) in ASP.NET Core. This mode allows the application to be compiled at runtime, offering faster startup and reduced memory consumption – suitable for cloud-native and microservices scenarios.
🔬 It is not enabled by default and requires runtime and build support, but it is an important step toward predictable performance in serverless environments.
🧹 2. Improved Trimming + Explicit Warnings
Preview 5 comes with advanced trimming analysis. Now you will receive clearer warnings during build if you use APIs incompatible with AOT or trimming (e.g., Assembly.Load, reflection, etc.).
✅ Recommendation: enable PublishTrimmed=true and EnableAotAnalyzer=true in Web projects to test compatibility.
⚙️ 3. Support for System.Text.Json Source Generator in More Complex Scenarios
The code generator for System.Text.Json is more capable: it can generate code for partial classes, inheritance, and generic structs. This means less runtime cost and more performance in large applications.
🧪 4. New Features in .NET SDK and CLI
Preview 5 also brings some new options in the CLI:
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dotnet publish --aot: option for more direct AOT publishing.
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dotnet workload update --include-previews: allows updating preview workloads.
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Diagnostic tools: better support for dotnet-counters and dotnet-trace.
📦 5. The System.Diagnostics.Metrics Library Has New Extensions
This library is increasingly used for observability. It now has better integration with OpenTelemetry and distributed analysis tools (traces, metrics, etc.).
💡 Other Interesting News
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CoreCLR continues to be optimized for startup time.
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Support for NativeAOT is expanding.
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MAUI receives stability fixes.
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Supported platforms are: Windows, Linux, macOS + integration with WASI for WebAssembly.
🗓️ When is the final version coming?
.NET 10 will be officially released in November 2025, during the .NET Conf conference. Monthly previews will continue until then, and community feedback is actively encouraged.
🔚 Conclusion
.NET 10 Preview 5 does not bring radical changes but continues to refine the fundamentals: performance, trimming, AOT, and developer experience. It is clear that Microsoft is focusing on modernizing the .NET ecosystem for cloud-native and edge computing scenarios.
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