What's new in .NET 11

This article describes new features in .NET 11. It was last updated for release candidate 1 (RC 1).

.NET 11 is currently in release candidate. General availability is expected in November 2026. You can download .NET 11 here.

#.NET runtime

The .NET 11 runtime includes:

• Updated minimum hardware requirements for x86/x64 and Arm64 architectures, requiring more modern instruction sets to improve performance and reduce maintenance complexity.
• Runtime-native async (Runtime Async), which produces cleaner stack traces and lower overhead. Runtime Async no longer requires <EnablePreviewFeatures>true</EnablePreviewFeatures> for projects that target net11.0. The runtime libraries themselves are compiled with runtime-async=on.
• Runtime Async performance improvements, including JIT compilation of a dedicated runtime-async version of synchronous task-returning methods, async continuations that opt out of ExecutionContext capture when no ambient state is in use, and tail-merged suspension points that reduce generated code size.
• Runtime Async tiered compilation, task and value-task factory intrinsics, and implicit tailcall improvements that reduce warm-up allocations and speed up common await paths.
• JIT improvements for bounds check elimination, redundant checked context removal, devirtualization, switch expression folding, constant-folding SequenceEqual, and redundant branch elimination. There are also new Arm SVE2 intrinsics, improved hardware-intrinsic cost modeling, and a faster Math.BigMul on x64 that emits a single MUL instruction.
• CoreCLR on WebAssembly now runs the libraries test suite end to end, and the runtime adds AVX-VNNI-512 hardware intrinsics for vectorized multiply-add workloads.
• In-process crash report logging that captures the managed stack trace and runtime state before the process exits, available on mobile platforms as well as Linux and macOS.
• NativeAOT faster interface dispatch using a shared dispatch helper, reducing binary size at call sites and improving throughput for interface-heavy workloads.
• SIMD lane construction and composition APIs (CreateGeometricSequence, Zip, Unzip, and the Concat family) across Vector128<T>, Vector256<T>, Vector512<T>, Vector64<T>, and Vector<T>.
• Hardware FP16 instructions for Half arithmetic and conversions on x64 and Arm64.

For more information, see What's new in the .NET 11 runtime.

#.NET libraries

The .NET 11 libraries include new APIs for:

• System.Diagnostics.Process expansion with run-and-capture helpers, fire-and-forget launches, Microsoft.Win32.SafeHandles.SafeProcessHandle lifecycle methods, tighter handle control, new System.Diagnostics.ProcessStartInfo.StartSuspended for suspended starts, System.Diagnostics.Process.TryGetProcessById(System.Int32,System.Diagnostics.Process@) for safe process lookup, and System.Diagnostics.Process.Signal(System.Runtime.InteropServices.PosixSignal) with System.Diagnostics.ProcessExitStatus for signaling processes and inspecting how they exited.
• Compression, including improved Base64 APIs, new methods for ZIP archive entries, Zstandard compression in System.IO.Compression, CRC32 validation when reading ZIP entries, and a Reset() method on the streamless Deflate, ZLib, and GZip encoders and decoders.
• New numeric APIs, including IEEE 754 decimal floating-point types (System.Numerics.Decimal32, System.Numerics.Decimal64, and System.Numerics.Decimal128), System.Numerics.INumberBase.TryParsePartial for delimiter-aware parsing, and generic System.Numerics.Complex.
• System.Text.Json improvements, including generic type info retrieval, System.Text.Json.JsonNamingPolicy.PascalCase, per-member naming policy overrides, type-level ignore conditions, F# discriminated union support, System.Text.Json.Utf8JsonWriter.Reset with options, SerializeAsyncEnumerable overloads for PipeWriter targets and top-level values (NDJSON) output, serialization of C# union types with the new JsonUnionTypeStructuralClassifier, built-in converters for BFloat16 and the new decimal floating-point types, and base64 schema metadata from JsonSchemaExporter.
• Built-in OpenTelemetry metrics for Microsoft.Extensions.Caching.Memory.MemoryCache.
• Discriminated-union scaffolding (UnionAttribute and IUnion) in System.Runtime.CompilerServices.
• Tar archive format selection and GNU sparse format 1.0 support.
• Console support for the FORCE_COLOR environment variable.
• TLS handshake hardening, certificate-validation alerts on Linux, channel binding validation on Unix, and an experimental caller-driven TLS session API (TlsBufferSession and TlsSocketSession).
• Networking additions, including HTTP request-body compression wrappers, configurable HTTP connection eviction, and typed DNS record resolution APIs on Windows, Linux, and macOS through System.Net.Dns and the new System.Net.DnsResolver class.
• HTTP/2 automatic downgrade for Windows authentication.
• LINQ join improvements, including FullJoin and tuple-returning Join and GroupJoin overloads, across System.Linq.Enumerable, System.Linq.Queryable, and System.Linq.AsyncEnumerable.
• A new System.Security.Cryptography.X25519DiffieHellman class for X25519 key exchange, and unpadded AES Key Wrap support (EncryptKeyWrap/DecryptKeyWrap) on System.Security.Cryptography.Aes.
• Generic overloads on System.Random — NextInteger<T> and NextBinaryFloat<T> — that work with any numeric generic type.
• System.Collections.Generic.EqualityComparer.Create factory method that creates a comparer from a key selector.
• System.Net.Quic.QuicStream.Priority for HTTP/3 stream prioritization.
• Video MIME type constants in System.Net.Mime.MediaTypeNames.Video.
• Four new Stream types (ReadOnlyMemoryStream, WritableMemoryStream, ReadOnlySequenceStream, StringStream) that wrap in-memory data without copying.
• System.Collections.BitArray constructors that accept ReadOnlySpan<bool>, ReadOnlySpan<byte>, and ReadOnlySpan<int>.
• Asynchronous validation in System.ComponentModel.DataAnnotations via AsyncValidationAttribute, IAsyncValidatableObject, and new Validator.ValidateObjectAsync methods, along with asynchronous Microsoft.Extensions.Options validation through IAsyncStartupValidator.
• Activity tracing configuration using rules in Microsoft.Extensions.Diagnostics, enabling declarative control of Activity tracing without wiring up ActivityListener instances manually.
• Cross-lane vector operations including CreateGeometricSequence, Zip, Unzip, and the Concat family on Vector128<T>, Vector256<T>, Vector512<T>, Vector64<T>, and Vector<T>.

For more information, see What's new in the .NET 11 libraries.

#.NET SDK

The .NET 11 SDK includes:

• Smaller SDK installers on Linux and macOS through assembly deduplication, with additional savings by skipping crossgen for DotnetTools-only assemblies.
• Improved CA1873 code analyzer with reduced noise and clearer diagnostic messages.
• Support for creating and editing solution filters (.slnf) from the dotnet sln CLI.
• File-based app support for #:include to split apps across multiple files and to include compiled DLL references directly, plus Native AOT build-output reuse and dotnet format support for file-based apps.
• A new dotnet run -e option to pass environment variables from the command line.
• dotnet watch improvements, including Aspire app-host integration, automatic crash recovery, and device selection for MAUI and mobile projects.
• OpenTelemetry replaces Application Insights for CLI telemetry.
• NativeAOT CLI entry point that serves the full command surface—including --help for all built-in commands and tool/external-command launches—out-of-process from the AOT path, skipping managed CLI startup.
• NativeAOT CLI and the MSBuild server are now enabled by default.
• dotnet test improvements, including --no-dependencies, DOTNET_TEST_RUNNER environment variable, --use-current-runtime, --test-modules exclusion patterns, per-assembly test counts, and live display of in-flight tests.
• dotnet test support for Android, iOS, macOS, and Mac Catalyst test projects, with device selection and new androidtest, iostest, macostest, and maccatalysttest templates.
• Additional dotnet test run-level options, including --timeout, --maximum-failed-tests, --results-directory-layout per-module, and an experimental affected-test workflow, along with traversal-project support, JSON output for --list-tests, and artifact post-processing for multi-module runs.
• Built-in test templates support xUnit v3 (defaulting to Microsoft.Testing.Platform) and NUnit with an opt-in --test-runner option.
• Multi-architecture container image builds with Podman using the SDK's container publishing support.
• Container publishing now prefers platform-native local runtimes (wslc on Windows and container on macOS) before Docker and Podman, produces reproducible image digests through SOURCE_DATE_EPOCH, and skips redundant layer uploads when the target manifest already exists.
• TypeScript compilation outputs from Razor Class Libraries now integrate correctly with the Static Web Assets pipeline.
• dotnet format limits .editorconfig discovery in folder mode to the ancestor directories of included files.
• The dotnet CLI no longer suppresses the MSBuild build server when DOTNET_CLI_USE_MSBUILD_SERVER is unset, and the OTLP telemetry exporter activates on any standard OTEL_EXPORTER_OTLP_* environment variable.

For more information, see What's new in the SDK for .NET 11.

#ASP.NET Core

For information about what's new in ASP.NET Core, see What's new in ASP.NET Core for .NET 11.

#C# 15

C# 15 is the default language version for projects that target .NET 11 and includes these features:

• Collection expression arguments
• Union types
• Closed hierarchies
• Extension indexers
• Labeled break and continue
• Memory safety

For information about new C# features, see What's new in C# 15.

#EF Core

See What's new in EF Core for .NET 11.

#Extensions libraries

See dotnet/extensions release notes.

#Windows Forms

See What's new in Windows Forms for .NET 11.

#WPF

See What's new in WPF in .NET 11.

#See also

• What's new in .NET 10