✅ asp.net BodyReader

var reader = HttpContext.Request.BodyReader;
var rawBody = Encoding.UTF8.GetString((await reader.ReadAsync()).Buffer);
var ((name, capacity, isPublic), error) = JsonUtils.Deserialize<PostRoomRequestBody>(rawBody);
await reader.CompleteAsync();

fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HMSD270MT6R7", Request id "0HMSD270MT6R7:00000001": An unhandled exception was thrown by the application.
      Microsoft.AspNetCore.Connections.ConnectionAbortedException: The connection was aborted by the application.
       ---> System.InvalidOperationException: Reading is already in progress.
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Http1ContentLengthMessageBody.TryReadInternal(ReadResult& readResult)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Http1MessageBody.OnConsumeAsync()
         --- End of inner exception stack trace ---