Incorrect OpenApi documentation in Minimal API when using WithOpenApi extension method

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I’m using .NET 7.0. I have created a Minimal API with the following endpoint:

app.MapDelete("api/people/{id:int}", Results<NoContent, NotFound> (int id) =>
{
    return id > 0 ? TypedResults.NoContent() : TypedResults.NotFound();
});

This produces the following page in Swagger:

In particular, the description of the 404 response is correctly “Not Found”.

However, if I add the WithOpenApi extension method to the endpoint, like this:

app.MapDelete("api/people/{id:int}", Results<NoContent, NotFound> (int id) =>
{
    return id > 0 ? TypedResults.NoContent() : TypedResults.NotFound();
})
.WithOpenApi(operation =>
{
    operation.Summary = "Deletes a person given the ID";
    operation.Description = "If the person does not exist, a 404 response is returned";
    return operation;
});

I obtain this:

So, the 404 response now has the description “Client error”, which is incorrect.

Expected Behavior

The description of 404 response should be “Not Found” even when I use the WithOpenApi extension method.

Steps To Reproduce

Minimal repro here: https://github.com/marcominerva/OpenApiIssue.

Exceptions (if any)

No response

.NET Version

7.0.100

Anything else?

Visual Studio 2022 17.4.1

.NET SDK: Version: 7.0.100 Commit: e12b7af219

Ambiente di runtime: OS Name: Windows OS Version: 10.0.22621 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\7.0.100\

Host: Version: 7.0.0 Architecture: x64 Commit: d099f075e4

.NET SDKs installed: 7.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed: Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 3.1.31 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.1.31 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 6.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 6.0.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.WindowsDesktop.App 3.1.31 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 6.0.9 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 6.0.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found: x86 [C:\Program Files (x86)\dotnet] registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables: Not set

global.json file: Not found

[captainsafia]

@marcominerva Thank you for reporting the issue and submitting a PR! I’ve opened a backport to .NET 7 so we can fix it there too. 🙇🏽

[marcominerva]

Thank you for the workaround, I’ll try to make a PR with the fix as soon as possible!