[dotnet-sdk-10.0.100-alpha.1.25057.15] CleanArchitecture1 get error: System.TypeLoadException: Method 'get_Description' in type 'FastEndpoints.ProducesResponseTypeMetadata' from assembly FastEndpoints does not have an implementation.

[Junjun-zhao]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When run the 3rd party application with the latest .NET 10 build, it failed with error: System.TypeLoadException: Method 'get_Description' in type 'FastEndpoints.ProducesResponseTypeMetadata' from assembly 'FastEndpoints, Version=5.27.0.0, Culture=neutral, PublicKeyToken=null' does not have an implementation.

Application Name: CleanArchitecture1
OS： Windows 10 22H2
CPU: X64
.NET Build Number: dotnet-sdk-10.0.100-alpha.1.25057.15
App & Source Location checking at: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2338907
Github Link: https://github.com/ardalis/CleanArchitecture

Verify Scenarios:
1). Windows 10 22H2 AMD64 + dotnet-sdk-9.0.102: Pass
2). Windows 10 22H2 AMD64 + dotnet-sdk-10.0.100-alpha.1.25057.15: Fail

Expected Behavior

Launch successfully.

Steps To Reproduce

App Repro Steps:

1. Copy AppSource\SourceShare\CleanArchitecture1to your local machine .
2. Open "CleanArchitecture1\App\CleanArchitecture1\Clean.Architecture.Web.runtimeconfig.json" file .
3. Change the "Clean.Architecture.Web.runtimeconfig.json" file to let the app run against with

dotnet-sdk-10.0.100-alpha.1.25057.15.
    "frameworks": [
     {
        "name": "Microsoft.NETCore.App",
        "version": "10.0.0-alpha.1.25052.4"
      },
      {
        "name": "Microsoft.AspNetCore.App",
        "version": "10.0.0-alpha.2.25056.9"
      }
    ]

4. Run the ”CleanArchitecture1\App\CleanArchitecture1\Clean.Architecture.Web.exe”.
5. Open edge and go to "http://localhost:5000/swagger/index.html".

Expected Result:
Launch successfully.

Actual Result:
Launch failed with error:

System.TypeLoadException: Method 'get_Description' in type 'FastEndpoints.ProducesResponseTypeMetadata' from assembly 'FastEndpoints, Version=5.27.0.0, Culture=neutral, PublicKeyToken=null' does not have an implementation.

Minimal Repro steps (Demo attached:WebApiDemo.zip):

1. Create a default8.0 asp web api.
2. Install FastEndpoints.Swagger 5.33.0.0.
3. Copy the following code to replace code in Program.cs.

using FastEndpoints;
using FastEndpoints.Swagger;
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddFastEndpoints().SwaggerDocument();
var app = builder.Build();
app.UseFastEndpoints().UseSwaggerGen();
app.Run();

4. Create MyEndpoint.cs with below code.

using FastEndpoints;
namespace WebApiDemo
{
    public class MyEndpoint : Endpoint<MyRequest, MyResponse>
    {
        public override void Configure()
        {
            Post("/Test");
            Description(b => b.ProducesProblemDetails(400));
        }
        public override async Task HandleAsync(MyRequest r, CancellationToken c)
        {
            await SendAsync(new()
            {
                Name = "Test"
            });
        }
    }
    public class MyRequest
    {
        public int Id { get; set; }
    }
    public class MyResponse
    {
        public string Name { get; set; }
    }
}

5. Publish the app with command "dotnet publish".
6. Change the runtime.config file to let the app run against with dotnet-sdk-10.0.100-alpha.1.25057.15.

    "frameworks": [
     {
        "name": "Microsoft.NETCore.App",
        "version": "10.0.0-alpha.1.25052.4"
      },
      {
        "name": "Microsoft.AspNetCore.App",
        "version": "10.0.0-alpha.2.25056.9"
      }
    ]

6. Launch the app by WebApiDemo.exe.
7. Open edge and go to "http://localhost:5000/swagger/index.html".

Expected Result:
Launch successfully.

Exceptions (if any)

Actual Result:
Launch failed with error:
System.TypeLoadException: Method 'get_Description' in type 'FastEndpoints.ProducesResponseTypeMetadata' from assembly 'FastEndpoints, Version=5.33.0.0, Culture=neutral, PublicKeyToken=null' does not have an implementation.

.NET Version

10.0.100-alpha.1.25057.15

Anything else?

Dotnet info:

.NET SDK:
 Version:           10.0.100-alpha.1.25057.15
 Commit:            39da6dde11
 Workload version:  10.0.100-manifests.a166a9cf
 MSBuild version:   17.14.0-preview-25056-07+8d395fd27

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19045
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\10.0.100-alpha.1.25057.15\

Host:
  Version:      10.0.0-alpha.1.25052.4
  Architecture: x64
  Commit:       efdd299533

.NET SDKs installed:
  10.0.100-alpha.1.25057.15 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 10.0.0-alpha.2.25056.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 10.0.0-alpha.1.25052.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 10.0.0-alpha.1.25056.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

@dotnet-actwx-bot @dotnet/compat

[maritogram]

It seems that FastEndpoints (version 5.33.0) uses its own implementation of IProducesResponseTypeMetadata from AspNetCore, however that interface was recently changed to include a Description property. This means that trying to cast (with the newest build) the interface into FastEndpoints' custom type will not work as it does not yet implement that Description property. I don't think this is an issue related to ASP.NET Core itself.

[Junjun-zhao]

Thank you @maritogram ,@gfoidl. We will file an issue to the app owner to notify him/her about this change. Is this an intentional by design change or breaking change?

[Junjun-zhao]

Gentle ping again @mkArtakMSFT @maritogram @gfoidl . Could you confirm if this is an intentional by design change or breaking change? Thanks.

[Junjun-zhao]

Hi @mkArtakMSFT @gfoidl @danroth27, as we haven't received the response, ping you again. This issue was tagged as External and we know it will need app owner to update in their side. But could you please double confirm if this change is an intentional by design change or breaking change? If this is a breaking change, a breaking change document will need to be filed, and we will also notify the app owner with it. Thanks.

[maritogram]

Hi @mkArtakMSFT @gfoidl @danroth27, as we haven't received the response, ping you again. This issue was tagged as External and we know it will need app owner to update in their side. But could you please double confirm if this change is an intentional by design change or breaking change? If this is a breaking change, a breaking change document will need to be filed, and we will also notify the app owner with it. Thanks.

Hey, I'm sorry, I don't think I have the expertise to answer whether this is an intentional or breaking change in ASP.NET Core. I hope you get your answer soon, best of luck.

[danroth27]

@captainsafia @joperezr Was this breaking change intentional? It looks like this is the related API review, but I don't see the breaking change mentioned: #55656.

[captainsafia]

@danroth27 The API proposal/approval was certainly intentional. I don't think we fully discussed that the introduction of a new property without a default implementation is a break for implementors of the API during the review process. We can file a breaking change issue for this.

[danroth27]

I don't think we fully discussed that the introduction of a new property without a default implementation is a break for implementors of the API during the review process

@captainsafia Should we provide a default implementation to avoid the breaking change?

[captainsafia]

@dj-nitehawk Heads up for your visibility. We introduced a new Description property on the ProducesResponseTypeMetadata to support being able to set descriptions on resposnse types that map to descriptions in OpenAPI documents.

Thoughts on a default implementation (likely an empty string) versus requiring an explicit implementation on the FastEndpoints.ProducesResponseTypeMetadata type?

[dj-nitehawk]

@captainsafia
what if you guys just added the new property only for >= net10 and a default implementation for everything else?

public interface IProducesResponseTypeMetadata
{
    Type? Type { get; }

    int StatusCode { get; }

#if NET10_0_OR_GREATER
    string? Description { get; }
#else
    string? Description => null;
#endif

    IEnumerable<string> ContentTypes { get; }
}

[Junjun-zhao]

@captainsafia @dj-nitehawk Thanks for looking into this issue. Could you please update in this bug when the final decision is made for this issue? Thanks.