ValidationProblemDetails errors ignored by problem details writer

[adam-dradrach-aspire]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Currently, when writing passing ValidationProblemDetails/HttpValidationProblemDetails to default IProblemDetailsService/IProblemDetailsWriter implementations - ValidationProblemDetails/HttpValidationProblemDetails errors prop is being removed and type is overridden by base ProblemDetails.

	public ValueTask WriteAsync(ProblemDetailsContext context)
	{
		if ((context.AdditionalMetadata?.GetMetadata<IApiBehaviorMetadata>() ?? context.HttpContext.GetEndpoint()?.Metadata.GetMetadata<IApiBehaviorMetadata>()) == null || _apiBehaviorOptions.SuppressMapClientErrors)
		{
			return ValueTask.CompletedTask;
		}
		ProblemDetails problemDetails = _problemDetailsFactory.CreateProblemDetails(context.HttpContext, context.ProblemDetails.Status ?? context.HttpContext.Response.StatusCode, context.ProblemDetails.Title, context.ProblemDetails.Type, context.ProblemDetails.Detail, context.ProblemDetails.Instance);
		if (context.ProblemDetails?.Extensions != null)
		{
			foreach (KeyValuePair<string, object> extension in context.ProblemDetails.Extensions)
			{
				problemDetails.Extensions[extension.Key] = extension.Value;
			}
		}
		OutputFormatterWriteContext context2 = new OutputFormatterWriteContext(context.HttpContext, _writerFactory.CreateWriter, typeof(ProblemDetails), problemDetails);
		IOutputFormatter outputFormatter = _formatterSelector.SelectFormatter(context2, Array.Empty<IOutputFormatter>(), _problemContentTypes);
		if (outputFormatter == null)
		{
			return ValueTask.CompletedTask;
		}
		return new ValueTask(outputFormatter.WriteAsync(context2));
	}

Expected Behavior

IProblemDetailsService/IProblemDetailsWriter implementation should not remove ValidationProblemDetails/HttpValidationProblemDetails errors.

Steps To Reproduce

Create validation and pass it to default problem details service/writer:

Output after writing validation problem details with problem details service/writer:

{
    "type": "https://datatracker.ietf.org/doc/html/rfc7231#section-6.5.1",
    "title": "Bad Request",
    "status": 400,
    "detail": "A validation problem occured.",
    "traceId": "5e476057-e8c8-4994-b5f4-e5fcda6b8a8d",
    "timestamp": "2025-08-20T17:32:37.4152604+00:00"
}

Exceptions (if any)

No response

.NET Version

9.0.304

Anything else?

No response

[MihuBot]

I'm a bot. Here are possible related and/or duplicate issues (I may be wrong):

• DefaultProblemDetailsWriter does not serialize HttpValidationProblemDetails.Errors #45680
• When endpoint return ValidationProblem and has errors the property errors doesn't have values. #59052

[adam-dradrach-aspire]

closed as duplicate of #45680