✅ always gets the invalid data received

//clicking the save btn prompts this method to work
public async Task<IActionResult> Update(ListingProjects updatedUserModelRef)
    {
        if (updatedUserModelRef == null || updatedUserModelRef.ListingName == null)
        {
            if (Request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                return Json(new { success = false, message = "Invalid data received." }); //however it always falls into this invalid message..
            }
            return NotFound();
        }

//clicking the save btn prompts this method to work
public async Task<IActionResult> Update(ListingProjects updatedUserModelRef)
    {
        if (updatedUserModelRef == null || updatedUserModelRef.ListingName == null)
        {
            if (Request.Headers["X-Requested-With"] == "XMLHttpRequest")
            {
                return Json(new { success = false, message = "Invalid data received." }); //however it always falls into this invalid message..
            }
            return NotFound();
        }