删除 ActionResult .Net Core

问：

我收到错误“运算符”==“不能应用于此行类型为”string“和”int？“的操作数

      .FirstOrDefaultAsync(m => m.Id == id);

到目前为止，除了这种方法，我还没有尝试过任何东西。

  public class EditProfileController : Controller
{

    private readonly ApplicationDbContext db;
    private object _context;

    public EditProfileController(ApplicationDbContext Db)
    {
        db = Db;
    }
    public IActionResult Index()
    {
      List<ApplicationUser> listdata = db.Users
        .Select(user => new ApplicationUser()
        {
            Id =  user.Id,
            UserName = user.UserName,
            NormalizedUserName = user.NormalizedUserName,
                            Email = user.Email


            // Add the remainder properties
        }).ToList();
    return View(listdata);
    }
    [HttpGet]
    public ActionResult Edit(string id)
    {
        //Get user and return the Edit View
        ApplicationUser user = db.Users.Where(u => u.Id == id)
      .Select(u => new ApplicationUser()
      {
          Id = u.Id,
          UserName = u.UserName,
          NormalizedUserName = u.NormalizedUserName,
          Email = u.Email

          // Add the remainder properties
      }).FirstOrDefault();
        return View(user);
    }


    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Edit(ApplicationUser listdata)
    {
        if (ModelState.IsValid)
        {
            db.Entry(listdata).State = EntityState.Modified;
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        return View(listdata);
    }


    public async Task<IActionResult> Delete(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var user = await db.Users
            .FirstOrDefaultAsync(m => m.Id == id);
        if (user == null)
        {
            return NotFound();
        }

        return View(user);
    }


    [HttpPost, ActionName("Delete")]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> DeleteConfirmed(int id)
     {
        var user = await db.Users.FindAsync(id);
        db.Users.Remove(user);
        await db.SaveChangesAsync();
        return RedirectToAction(nameof(Index));
     }
  }

我的预期结果是，当我单击“查看”页面上的“删除”链接时，它会要求确认删除，然后在单击“是”或“否”后，它会执行 DeleteConfirmed 操作。我需要什么来修复这个错误？