Log in with different browsers MVC 4

Question

On my MVC 4 application I have a log in page which saves a user Id and transfers user to a Dashboard page in this way:

 var user = _userService.GetUserByCredentials(accountCredentials.Username.Trim(), accountCredentials.Password);

if (user != null)
{
    FormsAuthentication.SetAuthCookie(user.Id.ToString(), true);
    return RedirectToAction("Index", "Dashboard");
}

If I log in with, for ex. Chrome I get transfered nicely to http://localhost:63377/Dashboard on which I use User.GetUserId()(on Dashboard controller):

_user = _userService.GetUserById(User.GetUserId());
Session["NimbleUser"] = _user.Firstname + " " + _user.Lastname;

An error is thrown if I copy the url(http://localhost:63377/Dashboard) to a Firefox, IE,... my _user on Dashboard controller is then null, probably because User.GetUserId() is null. How do I repair this so I can copy url to other browsers and that my application still works?

Thanks in advance

Answer 1

The auth cookie is stored by the browser, for the browser. You'll have to perform the login with each of your browsers that you want to use.