ASP.NET Core 2 Unable to resolve service for type Microsoft EntityFrameworkCore DbContext

StudentService expects DbContext but the container does not know how to resolve it based on your current startup.

You would need to either explicitly add the context to the service collection


services.AddScoped<DbContext, SchoolContext>();
services.AddScoped<IStudentService, StudentService>();

Or update the StudentService constructor to explicitly expect a type the container knows how to resolve.


public StudentService(SchoolContext context)
    : base(context)

if dbcontext inherited from then it woud be added like that

    services.AddScoped(provider => new CDRContext());

    services.AddTransient<IUnitOfWork, UnitOfWorker>();
    services.AddTransient<ICallService, CallService>();

I encountered a similar error i.e.

An unhandled exception occurred while processing the request. InvalidOperationException: Unable to resolve service for type 'MyProjectName.Models.myDatabaseContext' while attempting to activate 'MyProjectName.Controllers.MyUsersController'.

Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, bool isDefaultParameterRequired)

What I later figured out was... I was missing the following line i.e. adding my database context to services:

services.AddDbContext<yourDbContext>(option => option.UseSqlServer("Server=Your-Server-Name\\SQLExpress;Database=yourDatabaseName;Trusted_Connection=True;"));

Here goes my ConfigureServices method defined in Startup class:

 public class Startup
        public Startup(IConfiguration configuration)
            Configuration = configuration;

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
            services.Configure<CookiePolicyOptions>(options =>
                // This lambda determines whether user consent for non-essential 
                //cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;

            services.AddDbContext<yourDbContext>(option => 


Basically, when you generated model classes from database, all your database tables were mapped into respective Model classes by creating the "New Scaffolded Item" and choosing the appropriate database context during the scaffolding procedure. Now, you need to manually register your database context as a service to the services parameter of ConfigureServices method.

Btw, rather than hard coding your connection string, you'll ideally pick it up from the configuration data. I have attempted to keep things simple here.