ExportController.cs

private readonly IViewRenderService viewRenderService;
private readonly IHtmlToPdfConverter htmlToPdfConverter;
private readonly IHostingEnvironment environment;

public DashboardController(
    IViewRenderService viewRenderService,
    IHtmlToPdfConverter htmlToPdfConverter,
    IHostingEnvironment environment)
{
    this.viewRenderService = viewRenderService;
    this.htmlToPdfConverter = htmlToPdfConverter;
    this.environment = environment;
}

[HttpGet]
public async Task<IActionResult> GetPdf(SomeInputModel input)
{
    var model = this.GetViewModel(input);
    var htmlData = await this.viewRenderService.RenderToStringAsync("~/Views/Dashboard/GetPdf.cshtml", model);
    var fileContents = this.htmlToPdfConverter.Convert(this.environment.ContentRootPath, htmlData);
    return this.File(fileContents, "application/pdf");
}

Could not find an IRouter associated with the ActionContext. If your application is using endpoint routing then you can get a IUrlHelperFactory with dependency injection and use it to create a UrlHelper, or use Microsoft.AspNetCore.Routing.LinkGenerator.)