How to enable HTTP2 in Kestrel

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IIS is not involved. Everything is running on local computer, Windows 10 x64. Tried creating different kinds of projects, like Blazor and Web API, the result is on the screenshot - invalid response, although in IE 11 it shows some weird characters. Chrome and MS Edge don't even try to display the page.

In the code below I tried different combinations of protocols, on the same port and IP or different ones. Only endpoints using HTTP1 work fine. Suggestions here didn't help.

How do I enable HTTP2 in Kestrel?

public static IWebHostBuilder CreateHostBuilder(string[] args)
{
  var configuration = new ConfigurationBuilder()
    .AddCommandLine(args)
    .Build();

  var environment = WebHost
    .CreateDefaultBuilder(args)
    .UseConfiguration(configuration)
    .UseIISIntegration()
    .UseContentRoot(Directory.GetCurrentDirectory())
    //.UseUrls("http://localhost:5000", "https://localhost:5001")
    .UseStaticWebAssets()
    .UseStartup<Startup>()
    .ConfigureKestrel(options =>
    {
      //options.ConfigureEndpointDefaults(o => o.Protocols = HttpProtocols.Http2);
      options.Listen(IPAddress.Loopback, 0, o =>
      {
        //o.UseHttps("Certificate.pfx", "Demo");
        o.Protocols = HttpProtocols.Http2;
      });

      options.Listen(IPAddress.Loopback, 0, o =>
      {
        o.UseHttps("Certificate.pfx", "Demo");
        o.Protocols = HttpProtocols.Http1;
      });
    });

  return environment;
}

IE 11 vs MS Edge

asp.net-core asp.net
1 Answers

https is required for http2
This works fine for net5.0 (checked in Chrome with protocol column enabled)

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.ConfigureKestrel(options =>
            {
                options.Listen(IPAddress.Any, 5000, o =>
                {
                    o.Protocols = HttpProtocols.Http2; // with this line or not - both works fine
                    o.UseHttps();
                });
            });
            webBuilder.UseStartup<Startup>();
        });

As per the docs

Starting with .NET Core 3.0, HTTP/2 is enabled by default

Use HTTP/2 with the ASP.NET Core Kestrel web server

user_14793350
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