Asp.Net Core Dependency Injection Error: Unable to Resolve Service for Type While Attempting to Activate

ASP.NET Core Dependency Injection error: Unable to resolve service for type while attempting to activate

To break down the error message:

Unable to resolve service for type 'WebApplication1.Data.BloggerRepository' while attempting to activate 'WebApplication1.Controllers.BlogController'.

That is saying that your application is trying to create an instance of BlogController but it doesn't know how to create an instance of BloggerRepository to pass into the constructor.

Now look at your startup:

services.AddScoped<IBloggerRepository, BloggerRepository>();

That is saying whenever a IBloggerRepository is required, create a BloggerRepository and pass that in.

However, your controller class is asking for the concrete class BloggerRepository and the dependency injection container doesn't know what to do when asked for that directly.

I'm guessing you just made a typo, but a fairly common one. So the simple fix is to change your controller to accept something that the DI container does know how to process, in this case, the interface:

public BlogController(IBloggerRepository repository)
//                    ^
//                    Add this!
{
    _repository = repository;
}

Note that some objects have their own custom ways to be registered, this is more common when you use external Nuget packages, so it pays to read the documentation for them. For example if you got a message saying:

Unable to resolve service for type 'Microsoft.AspNetCore.Http.IHttpContextAccessor' ...

Then you would fix that using the custom extension method provided by that library which would be:

services.AddHttpContextAccessor();

For other packages - always read the docs.

.NET Core dependency injection error : "Unable to resolve service for type 'AspNetCoreWebAPI.Data.IBookRepository'"

You can add this code in your programer.cs :

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddControllers();

builder.Services.AddScoped<IBookRepository, BookRepository>();
//.......

ASP.NET Core Dependency Injection error - Unable to resolve service for type "Repository" while attempting to activate "Service"

In the GameService change it so it uses the IGameRepository interface like so:

public class GameService : IGameService
{
    private IGameRepository gameRepo;

    public GameService(IGameRepository gameRepo)
    {
        this.gameRepo = gameRepo;
    }
}

FYI, GameRepository can't be resolved because you've configured the dependency injection to inject the repository when the interface IGameRepository is used in the constructor not the concrete implementation.

How do I resolve "Unable to resolve service for type '' while attempting to activate ''"

The quick fix would be to change the controller constructor to depend on the abstraction instead of the implementation since the abstraction is what was registered with the container.

//...

private readonly ApplicationDbContext _context;
private readonly IAsyncPaymentsService<PaymentDetail> _service;

public PaymentController(ApplicationDbContext context, IAsyncPaymentsService<PaymentDetail> service)
{
    _context = context;
    _service = service;
}

//...

However, the generic abstraction could derived to a closed type if so desired

public interface IPaymentService :  IAsyncPaymentsService<PaymentDetail> {

}

applied to the implementation

public class PaymentService : IPaymentService {
    //...omitted for brevity
}

registered with the container

services.AddTransient<IPaymentService, PaymentService>();

and refactored in the controller

//...

private readonly ApplicationDbContext _context;
private readonly IPaymentService _service;

public PaymentController(ApplicationDbContext context, IPaymentService service)
{
    _context = context;
    _service = service;
}

//...

.NET 6 ... unable to resolve service for type

Auto generated code assumes you have setup dependency registration already. In your case you have not added JMSContext to the dependency container.

You need to add JMSContext to the DI

If you are using Startup file, then you can do

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<JMSContext>(options => options.UseSqlServer(Configuration.GetConnectionString("YourConnectionStringKeyName_From_AppSettings.json"));
    //----- rest of the code
}

and if you are not using Startup file, then in your Program.cs file, before building the app, you can use

builder.Services.AddDbContext<JMSContext>(options => options.UseSqlServer(Configuration.GetConnectionString("YourConnectionStringKeyName_From_AppSettings.json"));

ASP.Net Core - Unable to resolve service for type *Context while attempting to activate *Controller

Look like you are missing out inject SFTPContext which is the DbContext to DI container.

Program.cs

builder.Services.AddDbContext<SFTPContext>(options =>
   options.UseSqlServer(builder.Configuration.GetConnectionString(/* ConectionString key from appsettings.json */)));

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Reference

Dependency injection (services) - ASP.NET Core fundamentals | Microsoft Docs

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