Controller doesnt seem to be pulling a value

Question

I am trying to create a table that lists the users in the system and their role. I keep running into a problem where its saying the model is null. I am quite new to asp so I think the value I set arent actually pulling values and why the view is crashing, but I have no idea why. I think this is like the last little piece of ASP I cant seem to wrap around.

My Controller

public class UserRolesController : Controller
{
    private readonly UserManager<ApplicationUser> _userManager;
    private readonly RoleManager<IdentityRole> _roleManager;
    public UserRolesController(UserManager<ApplicationUser> userManager, RoleManager<IdentityRole> roleManager)
    {
        _roleManager = roleManager;
        _userManager = userManager;
    }
    public async Task<IActionResult> Administration()
    {
        var users = await _userManager.Users.ToListAsync();
        var userRolesViewModel = new List<UserRolesViewModel>();
        foreach (ApplicationUser user in users)
        {
            var thisViewModel = new UserRolesViewModel();
            thisViewModel.UserId = user.Id;
            thisViewModel.Email = user.Email;
            thisViewModel.FirstName = user.FirstName;
            thisViewModel.LastName = user.LastName;
            thisViewModel.Roles = await GetUserRoles(user);
            userRolesViewModel.Add(thisViewModel);
        }
        return View(userRolesViewModel);
    }
    private async Task<List<string>> GetUserRoles(ApplicationUser user)
    {
        return new List<string>(await _userManager.GetRolesAsync(user));
    }

    public async Task<IActionResult> Manage(string userId)
    {
        ViewBag.userId = userId;
        var user = await _userManager.FindByIdAsync(userId);
        if (user == null)
        {
            ViewBag.ErrorMessage = $"User with Id = {userId} cannot be found";
            return View("NotFound");
        }
        ViewBag.UserName = user.UserName;
        var model = new List<ManageUserRolesViewModel>();
        foreach (var role in _roleManager.Roles.ToList())
        {
            var userRolesViewModel = new ManageUserRolesViewModel
            {
                RoleId = role.Id,
                RoleName = role.Name
            };
            if (await _userManager.IsInRoleAsync(user, role.Name))
            {
                userRolesViewModel.Selected = true;
            }
            else
            {
                userRolesViewModel.Selected = false;
            }
            model.Add(userRolesViewModel);
        }
        return View(model);
    }
    [HttpPost]
    public async Task<IActionResult> Manage(List<ManageUserRolesViewModel> model, string userId)
    {
        var user = await _userManager.FindByIdAsync(userId);
        if (user == null)
        {
            return View();
        }
        var roles = await _userManager.GetRolesAsync(user);
        var result = await _userManager.RemoveFromRolesAsync(user, roles);
        if (!result.Succeeded)
        {
            ModelState.AddModelError("", "Cannot remove user existing roles");
            return View(model);
        }
        result = await _userManager.AddToRolesAsync(user, model.Where(x => x.Selected).Select(y => y.RoleName));
        if (!result.Succeeded)
        {
            ModelState.AddModelError("", "Cannot add selected roles to user");
            return View(model);
        }
        return RedirectToAction("Administration");
    }
}

My User Model

   public class UserRolesViewModel
    {
        public string UserId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string UserName { get; set; }
        public string Email { get; set; }
        public IEnumerable<string> Roles { get; set; }
    }

My Role Model

public class ManageUserRolesViewModel
{
    public string RoleId { get; set; }
    public string RoleName { get; set; }
    public bool Selected { get; set; }

}

And my View where the program crashes on the foreach statement

@{
    ViewData["Title"] = "Administration";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
<h1>User Roles</h1>
<table class="table table-striped">
    <thead>
        <tr>
            <th>First Name</th>
            <th>Last Name</th>
            <th>Email</th>
            <th>Roles</th>
            <th>Action</th>
        </tr>
    </thead>
    <tbody>
        @foreach (var user in Model)
        {
        <tr>
            <td>@user.FirstName</td>
            <td>@user.LastName</td>
            <td>@user.Email</td>
            <td>@string.Join(" , ", user.Roles.ToList())</td>
            <td>
                <a class="btn btn-primary" asp-controller="UserRoles" asp-action="Manage" asp-route-userId="@user.UserId">Manage Roles</a>
            </td>
        </tr>
        }
    </tbody>
</table>