A public action method 'subscriber' was not found on controller 'NewsletterController'

Question

I am getting this error as a warning from the elmah error log. Actually I have no method on controller named "subscriber". I have explored this solutions also

A public action method '..' was not found on controller '..'

But all the issue is I haven't method called "subscriber" in my controller.

Here is my Newsletter controller.

  public class NewsletterController : Controller
    {
        private readonly NewsletterService _newsletterService;

        public NewsletterController(NewsletterService newsletterService)
        {
            _newsletterService = newsletterService;
            ;
        }

        [Route("newsletter/sign-up")]
        [HttpPost]
        public async Task<ActionResult> SignUp(NewsletterSignUpModel model)
        {
            if (ModelState.IsValid)
            {
                await _newsletterService.SignUp(model);
            }

            return View("Index");
        }
    }

_newsletterService.SignUp() this method calls the campaign monitor to subscribe the user.

Elmah error log says

I have searched in project for particular url "newsletter/subscriber/new" and also separate words. but nothing found.

Any type of help will be appreciated.