How change username in Identity 3?

Question

I want crud operation for Identity user. When i click on submit button it show me error

ArgumentNullException: Value can not be null. Parameter name: provider atMicrosoft.Extensions.DependencyInjection.ServiceProviderExtensions.GetRequiredService[T](IServiceProvider provider)

UserController

public async Task<ActionResult> Edit([Bind("UserName,Id")] ApplicationUser formuser, string id, string RoleId)
{
    // ViewBag.RoleId = new SelectList(RoleManager.Roles, "Id", "Name");
    var userManager = serviceProvider.GetRequiredService<UserManager<ApplicationUser>>();
    var user = await userManager.FindByNameAsync(formuser.Email);
    user.UserName = formuser.UserName;

    if (ModelState.IsValid)
    {
        await userManager.UpdateAsync(user);
        return RedirectToAction("Index");
    }
    else
    {
        ViewBag.RoleId = new SelectList(RoleManager.Roles, "Id", "Name");
        return View();
    }
}