api-supported-versions header missing in error response for unspecified version

[mikekistler]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

In a minimal API project with Asp.Versioning implemented and configured with

    options.ReportApiVersions = true;

a request without an api-version receives an error response (as expected) but the api-supported-versions header is not included in the response.

It appears that a request with an invalid api-version (not conforming to the api-version convention) also gets an error response without an api-supported-versions header.

Expected Behavior

The api-supported-versions header should be present in the error response for unspecified version and invalid version.

These are errors where the client clearly does not understand the versioning convention of the API so these are really the most important responses to contain this header.

Steps To Reproduce

I created a simple Minimal API project and added Asp.Versioning, configuring it as described in the doc.

I ran the application and sent it a request without an api-version (expected in the query string).

GET {{HostAddress}}/hello
Accept: application/json

The response is missing the api-supported-versions response header.

HTTP/1.1 400 Bad Request
Connection: close
Content-Type: application/problem+json
Date: Fri, 24 Jan 2025 02:38:56 GMT
Server: Kestrel
Transfer-Encoding: chunked

{
  "type": "https://docs.api-versioning.org/problems#unspecified",
  "title": "Unspecified API version",
  "status": 400,
  "detail": "An API version is required, but was not specified.",
  "traceId": "00-a372d549f9291f215504fd15cc7c910d-cf1810dc65cf702d-00"
}

Note that if I send a request with a valid but unsupported api-version, the header is included in the response.

GET {{HostAddress}}/hello?api-version=99
Accept: application/json

HTTP/1.1 400 Bad Request
Connection: close
Content-Type: application/problem+json
Date: Fri, 24 Jan 2025 02:49:00 GMT
Server: Kestrel
Transfer-Encoding: chunked
api-supported-versions: 1.0

{
  "type": "https://docs.api-versioning.org/problems#unsupported",
  "title": "Unsupported API version",
  "status": 400,
  "detail": "The HTTP resource that matches the request URI 'http://localhost:5217/hello' does not support the API version '99'.",
  "traceId": "00-e745de9e24e936b956f50c6bcbe772ab-b842c2c78538c1c3-00"
}

Exceptions (if any)

No response

.NET Version

9.0.100

Anything else?

Package versions:

<PackageReference Include="Asp.Versioning.Http" Version="8.1.0" />
<PackageReference Include="Asp.Versioning.Mvc.ApiExplorer" Version="8.1.0" />