Microsoft has released the fourth preview of .NET 10, bringing a range of enhancements across ASP.NET Core, Blazor, .NET MAUI, WPF, Entity Framework Core, and the runtime.
This version introduces a new JSON Patch implementation using System.Text.Json in ASP.NET Core, providing a more efficient alternative to the previous Newtonsoft.Json-based version. While it improves performance and reduces memory use, there is a note that the new implementation does not support dynamic types and is not a full drop-in replacement.
Furthermore, support for minimal API validation has been extended to record types, and developers can now generate OpenAPI schemas programmatically using transformers. These schemas can be dynamically added to OpenAPI documents using the newly added transformer context methods. Improved XML documentation integration now allows comments from external assemblies to be included, improving API documentation for types not defined in the main project.
Blazor enhancements in this release include a new NotFound method in NavigationManager to signal missing pages during rendering. Navigation behavior during static server-side rendering has also been aligned with interactive scenarios, removing the previously thrown NavigationException.
Blazor’s WebAssembly runtime now offers detailed diagnostic capabilities, enabling the collection of performance traces, memory dumps, and runtime metrics, although enabling this feature may increase app size and reduce performance.
(Blazor WebAssembly runtime diagnostics, Source: GitHub Release Notes)
JavaScript interop has been extended with new APIs to invoke constructors and access properties of JavaScript objects directly from .NET. Support has also been added for referencing JavaScript functions via IJSObjectReference.
Blazor WebAssembly apps now benefit from better runtime performance through preloading of static framework assets and the merging of the boot manifest into the dotnet.js file. Related template updates include support for import maps and improved asset fingerprinting via the OverrideHtmlAssetPlaceholders property.
Regarding the .NET MAUI, Preview 4 introduces improvements across multiple platforms, including nullable support in date and time pickers, enhanced media picking on mobile, and various bug fixes related to input and rendering behavior.
The WPF updates include refined Fluent theme styling for text-based controls and improvements to message boxes and the shared clipboard API. As reported, significant performance gains have been achieved through code cleanup and refactoring, while known issues affecting TextBox and DatePicker under the Fluent System theme mode are acknowledged and expected to be addressed in Preview 5.
Furthermore, Entity Framework Core 10 brings support for full-text search and hybrid search on Azure Cosmos DB, enabling more advanced search queries. Full-text search can now be modeled within the EF Core API and used directly in LINQ queries.
Additionally, vector similarity search, introduced experimentally in EF9, has now reached stable status with expanded capabilities, including support for owned reference entities.
Other changes in this release are improvements to WebApplicationFactory testing with Kestrel, enhanced OpenAPI.NET support, renamed APIs for consistency, and various refinements to EF Core SQL translation and performance.
Lastly, for interested readers, full release notes are available on the official .NET GitHub repository.
