In order to support the ASP.NET Core Identity service, our ApplicationDbContext class needs to be updated as well.

Open the Data/ApplicationDbContext.cs class file and perform the following changes:

1. Add a using reference to Microsoft.AspNetCore.Identity.EntityFrameworkCore, as required by the new base class:

using Microsoft.AspNetCore.Identity.EntityFrameworkCore; 

2. Change the base class from DbContext to IdentityDbContext<ApplicationUser>:

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public class ApplicationDbContext : IdentityDbContext<ApplicationUser> 

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3. Remove the DbSet<ApplicationUser> Users property, as the IdentityDbContext base class that we just inherited already has it built in:

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#region Properties
// public DbSet<ApplicationUser> Users { get; set; }
public DbSet<Quiz> Quizzes { get; set; }

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