title: Identity error: Value cannot be null.\r\nParameter name: manager
body: <p>I using ASP.NET Identity and when a user want to register get this error:</p>
  
  <blockquote>
    <p>Value cannot be null.\r\nParameter name: manager.</p>
  </blockquote>
  
  <p>Here is my Register Action code:</p>
  
  <pre><code>public virtual ActionResult Register(string nm, string em, string ps)
      {
          var redirectUrlPanel = new UrlHelper(Request.RequestContext).Action("Index", "HomeUsers", new { area = "Users" });
          var redirectUrlAuction = new UrlHelper(Request.RequestContext).Action("Auction", "Default", new { area = "" });
  
          if (ModelState.IsValid)
          {
              try
              {
                  var user = new Q_Users();
                  user.UserName = nm;
                  user.Email = em;
                  user.SecurityStamp = Guid.NewGuid().ToString();
  
                  var adminresult = UserManager.Create(user, ps);
  
                  //Add User Admin to Role Admin
                  if (adminresult.Succeeded)
                  {
                      //Find Role Admin
                      var role = RoleManager.FindByName("Admin");
                      var result = UserManager.AddToRole(user.Id, role.Name);
                      if (result.Succeeded)
                      {
                          return Json(new { OK = "1", UrlPanel = redirectUrlPanel, UrlAuction = redirectUrlAuction });
                      }
                  }
                  else
                  {
                      return Json(new { OK = "0", UrlPanel = redirectUrlPanel, UrlAuction = redirectUrlAuction });
                  }
              }
              catch (Exception ex) { }
              return Json(new { OK = "0", UrlPanel = redirectUrlPanel, UrlAuction = redirectUrlAuction });
          }
          else
          {
              return Json(new { OK = "0", UrlPanel = redirectUrlPanel, UrlAuction = redirectUrlAuction });
          }
      }
  </code></pre>
  
  <p>And the error in this Line: <code>var adminresult = UserManager.Create(user, ps);</code></p>