Implementation type Data.AppDbContext can't be converted to service type Microsoft.AspNetCore.Identity.IUserStore

この例外は、AddUserStore と AddRoleStore を使って user store と role store を指定せずに identity DbContext を構築しようとしたときにスローされます。

下の例のように、AddEntityFrameworkStores を 1 回呼び出すだけで両方の設定を行えます。

services.AddIdentity<IdentityUser, IdentityRole>(options =>
    {
        // Set your options here
    })
    .AddEntityFrameworkStores<FooDbContext>()
    .AddDefaultTokenProviders();

完全な例外メッセージは参考までに以下のとおりです。

System.AggregateException: ‘Some services are not able to be constructed (Error while validating the service descriptor ‘ServiceType: Microsoft.AspNetCore.Identity.IUserClaimsPrincipalFactory1[Areas.Identity.Data.ApplicationUser] Lifetime: Scoped ImplementationType: Areas.Identity.Data.AdditionalUserClaimsPrincipalFactory’: Unable to resolve service for type ‘Microsoft.AspNetCore.Identity.UserManager1[Areas.Identity.Data.ApplicationUser]’ while attempting to activate ‘Areas.Identity.Data.AdditionalUserClaimsPrincipalFactory’.)’