MVC Role users error instance

DPaul1994

I created a few roles for users and I'm trying to assing a role to a specific user but I get this error:

An exception of type 'System.NullReferenceException' occurred in Microsoft.Owin.Host.SystemWeb.dll but was not handled in user code

Additional information: Object reference not set to an instance of an object.

If there is a handler for this exception, the program may be safely continued.

and

Line 47: get
Line 48: {
Line 49: return _userManager ?? HttpContext.GetOwinContext().GetUserManager();
Line 50: }
Line 51: private set

In AccountController I don't have anything for this option. This is the function from Controller that should assing the role:

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult RoleAddToUser(string UserName, string RoleName)
{
ApplicationUser user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
var account = new AccountController();
account.UserManager.AddToRole(user.Id, "RoleName");

        ViewBag.ResultMessage = "Role created successfully !";

        // prepopulat roles for the view dropdown
        var list = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList();
        ViewBag.Roles = list;

        return View("ManageUserRoles");
    }

Where is the mistake?

Herman T Instance

Did you DEBUG your code? Where did the exception occur?

_userManager ?? HttpContext.GetOwinContext().GetUserManager();

What is _userManager AND HttpContext.GetOwinContext().GetUserManager() are NULL. What would then be the behaviour?

In Word you can only store 2 bytes. That is why I use Writer.