The ObjectContext instance has been disposed and can no longer be used for operations that require a connection in mvc5 view

Question

I'm trying to do a loop in mvc5 view for particular model properties but I'm getting an error:

Additional information: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.

This is the view I have:

@using App.Models
@model App.Portal.WebUI.Models.ManageViewModel

@{
    ViewBag.Title = "Edit";
}

<h2>Edit</h2>

<div class="container">
    <div class="col-md-9">
        <div class="col-md-12">
            <div class="form-group">
                @Html.LabelFor(m => m.AUser.Id)
                <label>@Html.DisplayFor(m => m.AUser.Id)</label>
            </div>
            <div class="form-group">
                @Html.LabelFor(m => m.AUser.FirstName)
                @Html.TextBoxFor(m => m.AUser.FirstName)
            </div>
            <div class="form-group">
                @Html.LabelFor(m => m.AUser.PhoneNumber)
                @Html.TextBoxFor(m => m.AUser.PhoneNumber)
            </div>
            <div class="form-group">
               
            </div>
        </div>
        <div class="col-md-12">
            <div class="form-group">&nbsp;</div>
            <div class="form-group">
                @Html.LabelFor(m => m.AUser.LastName)
                @Html.TextBoxFor(m => m.AUser.LastName)
            </div>
            <div class="form-group">
                @Html.LabelFor(m => m.AUser.Email)
                @Html.TextBoxFor(m => m.AUser.Email)
            </div>
        </div>
       
        
    </div>
    <div class="col-md-3">
            @foreach (AspNetRole userRole in Model.AUser.AspNetRoles)
            {
                    @Html.CheckBox(userRole.Name, true)
                    @Html.Label(userRole.Name)<br />
            }
    </div>
</div>

The error happens in the foreach loop.

Any idea what am I doing wrong?

Update

Code added:

ManageViewModel model = new ManageViewModel();

            if (id.HasValue)
            {
                using (var db = new DbContext())
                {
                    AspNetUser user = (from p in db.AspNetUsers
                                       where p.Id == id
                                       select p).First();
                    model.AUser = user;

                    List<AspNetRole> roles = (from r in db.AspNetRoles
                        select r).ToList();

                    model.RoleList = roles;
                }
            }

Answer 1

 @foreach (AspNetRole userRole in Model.RoleList)
            {
                    @Html.CheckBox(userRole.Name, true)
                    @Html.Label(userRole.Name)<br />
            }

Don't use Entities connected to the DB in your ViewModel! NEVER!! It causes issues like you have just encountered. Separate layers. Read about separation of concerns separation of concerns