Hey Philip, did you manage to resolve this? I need the same thing.

I struggled for a bit returning umbraco's configured not found page from my own virtual page controllers.

I'm not sure if our situation is the same (I'm on v15) but this is what I ended up with in case you are out of ideas.

return BrandedNotFound();


protected IActionResult BrandedNotFound()
{

    var notFoundPageKey = Guid.Parse("6ef29dbd-a6e9-4d8f-b72e-99a103361280");

    var notFoundPage = umbracoHelper.Content(notFoundPageKey);
    Response.StatusCode = 404;
    if (notFoundPage != null)
    {
        return View(notFoundPage!.GetTemplateAlias(), notFoundPage);
    }

    return NotFound(); // Unstyled

}

Where that guid is the one configured in my appsettings.json

"Error404Collection": [
  {
    "Culture": "default",
    "ContentKey": "6ef29dbd-a6e9-4d8f-b72e-99a103361280"
  }
]

Thanks npack,

We already did something similar. I will add it here in case someone finds it useful:

public override IActionResult Index()
{
    if (IsExpiredJob())
    {
        return HttpNotFoundPage();
    }

    return CurrentTemplate(CurrentPage);
}

private ViewResult HttpNotFoundPage()
{
    var home = CurrentPage.Root<HomePage>();
    Response.Clear();
    Response.StatusCode = (int)HttpStatusCode.NotFound;
    var error404 = home.DescendantOrSelf<Error404>();

    var contentModel = new ContentModel(error404);
    var viewData = new ViewDataDictionary(
        new Microsoft.AspNetCore.Mvc.ModelBinding.EmptyModelMetadataProvider(),
        new Microsoft.AspNetCore.Mvc.ModelBinding.ModelStateDictionary()
    )
    {
        Model = contentModel
    };

    var viewResult = new ViewResult
    {
        ViewData = viewData,
        ViewName = contentModel.Content.GetTemplateAlias(),
    };

    return viewResult;
}

It's for version 13 though.

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