HTTP/3 configuration in ASP.NET Core 6 preview 5 throws an error on startup

[JuergenGutsch]

Describe the bug

I tried to configure HTTP/3 as described in this post:
https://devblogs.microsoft.com/aspnet/asp-net-core-updates-in-net-6-preview-3/
This throws an error on startup:

Cannot start HTTP/3 server if no IMultiplexedConnectionListenerFactory is registered.

I stumbled upon that while writing a blog post about HTTP/3 in ASP.NET Core 6.

I had a quick search in the aspnetcore repo to find an implementation of the IMultiplexedConnectionListenerFactory, but just fon the implementation for the Quic transport. @JamesNK added the Quic transport to the HTTP/3 epic (#15271) does this mean HTTP/3 runs over Quic?

I tried to use quick to get it running, but I got different errors. I guess it is not yet ready in the preview 5.

To Reproduce

• create a new MVC project using dotnet new mvc
• add the code to configure HTTP/3 as shown in the blog post
• don't forget to add code to load a certificate
• run the application using dotnet run

Exceptions (if any)

Building...
warn: Microsoft.AspNetCore.Server.Kestrel[0]
      Overriding address(es) 'https://localhost:5001, http://localhost:5000'. Binding to endpoints defined via IConfiguration and/or UseKestrel() instead.
Unhandled exception. System.InvalidOperationException: Cannot start HTTP/3 server if no IMultiplexedConnectionListenerFactory is registered.
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.<>c__DisplayClass29_0`1.<<StartAsync>g__OnBind|0>d.MoveNext() in Microsoft.AspNetCore.Server.Kestrel.Core.dll:token 0x6001092+0x45
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindEndpointAsync(ListenOptions endpoint, AddressBindContext context, CancellationToken cancellationToken) in Microsoft.AspNetCore.Server.Kestrel.Core.dll:token 0x600041f+0x80
   at Microsoft.AspNetCore.Server.Kestrel.Core.ListenOptions.BindAsync(AddressBindContext context, CancellationToken cancellationToken) in Microsoft.AspNetCore.Server.Kestrel.Core.dll:token 0x60002fb+0x77
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.EndpointsStrategy.BindAsync(AddressBindContext context, CancellationToken cancellationToken) in Microsoft.AspNetCore.Server.Kestrel.Core.dll:token 0x6000f5c+0x9b
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindAsync(IEnumerable`1 listenOptions, AddressBindContext context, CancellationToken cancellationToken) in Microsoft.AspNetCore.Server.Kestrel.Core.dll:token 0x600041c+0xc7
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.BindAsync(CancellationToken cancellationToken) in Microsoft.AspNetCore.Server.Kestrel.Core.dll:token 0x600027d+0x193
   at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken) in Microsoft.AspNetCore.Server.Kestrel.Core.dll:token 0x600027a+0x108
   at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken) in Microsoft.AspNetCore.Hosting.dll:token 0x60000b0+0x235
   at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken) in Microsoft.Extensions.Hosting.dll:token 0x6000061+0x177
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token) in Microsoft.Extensions.Hosting.Abstractions.dll:token 0x600001e+0x93
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token) in Microsoft.Extensions.Hosting.Abstractions.dll:token 0x600001e+0x1be
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost host) in Microsoft.Extensions.Hosting.Abstractions.dll:token 0x600001d+0x15
   at Http3Tls.Program.Main(String[] args) in C:\git\hub\aspnetcore6\Http3Tls\Program.cs:line 19

Further technical details

dotnet --info
.NET SDK (reflecting any global.json):
 Version:   6.0.100-preview.5.21302.13
 Commit:    d6380bcae7

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19042
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.100-preview.5.21302.13\

Host (useful for support):
  Version: 6.0.0-preview.5.21301.5
  Commit:  ec3e0b276b

[BrennanConroy]

HTTP/3 isn't supported until preview 7.

[JuergenGutsch]

Thanks @BrennanConroy
Good to know. 👍 Unfortunately, that fact isn't mentioned in the blog post about the preview 3.
People (at least me) are trying the new features mentioned there.

[ytodorov]

It should be supported now:
https://devblogs.microsoft.com/aspnet/asp-net-core-updates-in-net-6-preview-7/?fbclid=IwAR1SxXImyZWBFkGHc4bh7WqvRBUK1c9M93C6Wz95K1VJ-TWJW6YrU2mIa5M#preview-support-for-http-3-in-kestrel