[Solved] Server.MapPath Not available in ASP.NET Core

It is not possible to use it. You need to use IHostingEnvironment for Core 2.0 and IWebHostEnvironment for Core 3.0 onwards.

You will need to inject a dependency in Controller as shown below.

WebRootPath is the path of the www folder in the solution and the Uploads folder will be created inside it.

public class HomeController : Controller
{
    private IHostingEnvironment Environment;

    public HomeController(IHostingEnvironment _environment)
    {
        Environment = _environment;
    }

    public IActionResult Index()
    {
        return View();
    }

    [HttpPost]
    public IActionResult Index(List<IFormFile> postedFiles)
    {
        string path = Path.Combine(this.Environment.WebRootPath, "Uploads");
        if (!Directory.Exists(path))
        {
            Directory.CreateDirectory(path);
        }

        return View();
    }
}