Updating user by UserManager.Update() in ASP.NET Identity 2

There is no need to pass the student as ApplicationUser to the UserManager.Update() method (because Student class inherits (hence is) ApplicationUser).

The problem with your code is that you are using new Student operator, thus creating a new student rather than updating the existing one.

Change the code like this:

// Get the existing student from the db
var user = (Student)UserManager.FindById(model.Id);

// Update it with the values from the view model
user.Name = model.Name;
user.Surname = model.Surname;
user.UserName = model.UserName;
user.Email = model.Email;
user.PhoneNumber = model.PhoneNumber;
user.Number = model.Number; //custom property
user.PasswordHash = checkUser.PasswordHash;

// Apply the changes if any to the db
UserManager.Update(user);

my answer on .netcore 1

this work for my, I hope can help them

var user = await _userManager.FindByIdAsync(applicationUser.Id);
                    user.ChargeID = applicationUser.ChargeID;
                    user.CenterID = applicationUser.CenterID;
                    user.Name  = applicationUser.Name;
var result = await _userManager.UpdateAsync(user);