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2026-08-02 csharp dotnet dotnet-11

How to configure Kestrel to serve HTTP/3 in ASP.NET Core 11

A complete guide to enabling HTTP/3 on Kestrel in ASP.NET Core 11: the HttpProtocols.Http1AndHttp2AndHttp3 endpoint config, MsQuic platform requirements on Windows, Linux, and macOS, why the first request is never HTTP/3, how to verify with HttpClient and middleware, QuicTransportOptions tuning, and the firewall and proxy gotchas that make it silently fall back.

2026-04-20 dotnet-11 aspnetcore kestrel

Kestrel starts processing HTTP/3 requests before the SETTINGS frame in .NET 11 Preview 3

.NET 11 Preview 3 lets Kestrel serve HTTP/3 requests before the peer's control stream and SETTINGS frame arrive, shaving handshake latency off the first request on every new QUIC connection.