Identity asp.net core 3.0 - IdentityDbContext not found : <p>My app broke with the 3.0 release of .NET core with reference errors for <code>IdentityDbContext</code>.  I'm looking through documentation for Identity on core 3.0 but it implies that IdentityDbContext should be there.  It's the only error I'm getting with a couple <code>DbContext</code> errors.</p>

<p>I have a pretty simple API, no MVC views, just a data server that gives back JSON objects.  It's based on Identity so it has the users and roles and claims.  And it's starting to take advantage of that.  My main DbContext extends <code>IdentityDbContext&lt;ApplicationUser&gt;</code> but after switching target platform to 3.0 after the upgrade, it says it doesn't exist and gives me compile errors.  Has anyone run into this?  Am I missing something?  The migration and breaking changes pages don't seem to have anything addressing my issue.</p>

<p>DbContext looks like this:</p>

<pre class="lang-cs prettyprint-override"><code>using System;
using Microsoft.AspNetCore.Identity;
//using Microsoft.AspNetCore.Identity.EntityFrameworkCore; &lt;- this no longer works either
using Microsoft.EntityFrameworkCore; //&lt;- this I had to download as a package
using App.Constants;
using App.Models.Identity;

namespace App.Models
{
    public class AppContext : IdentityDbContext&lt;ApplicationUser&gt; //&lt;- error is right here
    {
        ... my models
    }
}
</code></pre>
