Failed to load resource: the server responded with a status of 404 ()

Hello Sir, 

The Project i create will capture image from a document scanner device...I am using ASP.Net Core MVC

I'd just copied the API Controller for the sample...

>>> below, if the Map controller route like this, it works fine if this Controller is the startup page. 

app.UseEndpoints(endpoints =>{

        endpoints.MapControllerRoute(
            name: "default",
            pattern: "{controller=Default}/{action=Index}");
 });

(this is my Startup.cs)

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }

    app.UseHttpsRedirection();
    app.UseStaticFiles();

    app.UseRouting();

    app.UseAuthorization();
    app.UseSession();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllerRoute(
            name: "default",
            pattern: "{controller=Default}/{action=Index}");
    });

}    

>>> below, if the startup Map controller route like this, it will generate an error to the production server.. 

app.UseEndpoints(endpoints =>

{
    endpoints.MapControllerRoute(
        name: "Home",
        pattern: "{controller=Home}/{action=Index}");
});

>>> below is the API Controller located in CONTROLLER on the Folder "API"

using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.IO;

namespace FILMSv1.Controllers
{
    [Produces("application/json")]
    [Route("api/ImageUploadApi")]

    public class ImageUploadApiController : Controller
    {

        public ImageUploadApiController(IWebHostEnvironment enviroment)
        {
            _enviroment = enviroment;
        }



        private IWebHostEnvironment _enviroment;
        /// <summary>
        /// Gets an information about the web hosting environment an application is running in.
        /// </summary>
        public IWebHostEnvironment Enviroment
        {
            get { return _enviroment; }
        }



        [HttpPost]
        public IActionResult Post()
        {
            IFormCollection form = Request.Form;
            try
            {
                if (form != null)
                {
                    string imageFileName = form["fileName"];
                    if (imageFileName == null)
                        throw new ArgumentException("Request does not contain image file name.");

                    string imageFileAsBase64String = form["imageFileAsBase64String"];
                    if (imageFileAsBase64String == null)
                        throw new ArgumentException("Request does not contain image file data.");

                    byte[] imageFileBytes = Convert.FromBase64String(imageFileAsBase64String);

                    // get the image file extension
                    string fileExtension = Path.GetExtension(imageFileName).ToLower();
                    if (fileExtension != ".bmp" && fileExtension != ".jpg" && fileExtension != ".pdf" && fileExtension != ".png" && fileExtension != ".tif")
                        fileExtension = ".jpg";

                    string projectPath = Enviroment.WebRootPath;
                    string imagesFilePath = Path.Combine(projectPath, "Images");
                    if (!Directory.Exists(imagesFilePath))
                        Directory.CreateDirectory(imagesFilePath);
                    string fileName = string.Format("demo{0}", fileExtension);
                    string fullFilePath = Path.Combine(imagesFilePath, fileName);

                    // save uploaded image file to the server
                    System.IO.File.WriteAllBytes(fullFilePath, imageFileBytes);
                }
            }
            catch (Exception e)
            {
                return BadRequest(e.Message);
            }
            return Content("");
        }

    }
}

Pls help...Thank's sir...