Cannot consume scoped service applicationdbcontext from singleton

I am building an ASP.NET Core 6.0 web app, I created a site that uses Microsoft Identity which created the ApplicationDbContext.cs file:

public class ApplicationDbContext : IdentityDbContext
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }

    public DbSet<Settingw> Settings { get; set; }
}

Next I created a Settings repository and repository interface. Ran everything, tested and everything is working fine.

Now I'm trying to call the dbcontext from inside that repository and I'm getting an error

> Cannot consume scoped service applicationdbcontext from singleton

I'm stuck, not sure what I am doing wrong.

Here's my program.cs:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(connectionString));
builder.Services.AddDatabaseDeveloperPageExceptionFilter();

builder.Services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddEntityFrameworkStores<ApplicationDbContext>();
builder.Services.AddRazorPages();

builder.Services.AddSingleton<ISettingsRepository, SettingsRepository>(); //errors here

var app = builder.Build();

SettingsRepository.cs:

public class SettingsRepository : ISettingsRepository
{
    private readonly ApplicationDbContext _dbContext;

    public SettingsRepository(ApplicationDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    public Settings Settings()
    {
        return _dbContext.Settings.AsNoTracking().First();
    }
}

Like Steve Py mentioned in the comment, you need to change the lifetime of your settings repository service like this:

builder.Services.AddScoped<ISettingsRepository, SettingsRepository>();

EF contexts are Scoped lifetime by default.

• Singleton: service is created once and the same instance is returned for the next requests as well
• Scoped: created once per "scope", and since ASP.NET Core creates a scope for a request, this essentially means the service is created once per request in typical scenarios
• Transient: created every time the service is needed

You should not depend on services with a smaller lifetime.
In this case your repository (Singleton) is depending on the context (Scoped).
The issue would be that your repository is only created once but the context it depends on is a per-scope service and would be disposed when the request is done.
In this case lowering the lifetime of the repository is the correct choice.