[Blazor] Unhandled exception. System.ArgumentException: Comments cannot be stored in a JsonDocument

[enricoreich]

Describe the bug

I using the latest SDK (3.0.100-preview7-012627) and created a simple Blazor Server-Side App with
dotnet new blazorserverside, build it and run it and then I get this error:

Unhandled exception. System.ArgumentException: Comments cannot be stored in a JsonDocument, only the Skip and Disallow comment handling modes are supported. (Parameter 'readerOptions')
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.HandleException(Exception e)
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load(Boolean reload)
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load()
   at Microsoft.Extensions.Configuration.ConfigurationRoot..ctor(IList`1 providers)
   at Microsoft.Extensions.Configuration.ConfigurationBuilder.Build()
   at Microsoft.Extensions.Hosting.HostBuilder.BuildAppConfiguration()
   at Microsoft.Extensions.Hosting.HostBuilder.Build()
   at BlazorServerSideApp1.Program.Main(String[] args) in D:\Workspaces\_playground\Blazor\BlazorServerSideApp1\Program.cs:line 18

Program.cs Line 18:

To Reproduce

Steps to reproduce the behavior:

1. create a new Blazor Server-Side app with dotnet new blazorserverside -n {nameOfProject}
2. run dotnet build
3. run dotnet run
4. See error

Expected behavior

Kestrel should run without any error.

Additional context

dotnet --info:

.NET Core SDK (reflecting any global.json):
 Version:   3.0.100-preview7-012627
 Commit:    86a2e1fec8

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.18362
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.0.100-preview7-012627\

Host (useful for support):
  Version: 3.0.0-preview7-27826-01
  Commit:  d41f5ea7cc

.NET Core SDKs installed:
  2.1.700 [C:\Program Files\dotnet\sdk]
  2.1.800-preview-009696 [C:\Program Files\dotnet\sdk]
  2.2.300 [C:\Program Files\dotnet\sdk]
  3.0.100-preview7-012627 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview7.19325.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview7-27826-01 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.0-preview7-27826-01 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[pranavkm]

cc @BrennanConroy

[BrennanConroy]

There are a couple breaking changes in corefx that we haven't consumed yet, and as a result weird things like this happen.

We'll be consuming the corefx changes later today and hopefully by tomorrow there will be a new sdk that works.

[enricoreich]

SDK 3.0.100-preview7-012687 is working so far. Thanks!