Software1 hOctober 25, 2026, 13:45

.NET 11 adds async validation to DataAnnotations

.NET 11 introduces AsyncValidationAttribute, IAsyncValidatableObject and Validator.TryValidateObjectAsync, letting validation rules await database calls without blocking threads. The APIs arrived in Preview 6, and RC2 shipped on October 13, 2026 with a go-live license.

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.NET 11 adds async validation to DataAnnotations

AsyncValidationAttribute and IAsyncValidatableObject allow awaits inside validation rules
TryValidateObjectAsync checks properties concurrently: two lookups took 608 ms
validateAllProperties still defaults to off, same as the sync API
RC2 shipped on October 13, 2026; the release is not final yet

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.NET 11 adds async validation to DataAnnotations

.NET 11 adds FullJoin and selector-free LINQ join overloads

.NET 11 adds Process.RunAndCaptureText to avoid process deadlocks

C# 15 adds with() for collection constructor arguments

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