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

Question

I created an  NET Core MVC application and use Dependency Injection and Repository Pattern to inject a repository to my controller  However  I am getting an error      InvalidOperationException  Unable to resolve service for type  WebApplication1 Data BloggerRepository  while attempting to activate  WebApplication1 Controllers BlogController     Model  Blog cs   namespace WebApplication1 Models       public class Blog               public int BlogId   get  set            public string Url   get  set              DbContext  BloggingContext cs   using Microsoft EntityFrameworkCore  using WebApplication1 Models   namespace WebApplication1 Data       public class BloggingContext   DbContext               public BloggingContext DbContextOptions lt BloggingContext gt  options                base options                      public DbSet lt Blog gt  Blogs   get  set              Repository  IBloggerRepository cs  amp  BloggerRepository cs   using System  using System Collections Generic  using WebApplication1 Models   namespace WebApplication1 Data       internal interface IBloggerRepository   IDisposable               IEnumerable lt Blog gt  GetBlogs             void InsertBlog Blog blog            void Save             using System  using System Collections Generic  using System Linq  using WebApplication1 Models   namespace WebApplication1 Data       public class BloggerRepository   IBloggerRepository               private readonly BloggingContext  context           public BloggerRepository BloggingContext context                         context   context                     public IEnumerable lt Blog gt  GetBlogs                         return  context Blogs ToList                       public void InsertBlog Blog blog                         context Blogs Add blog                      public void Save                          context SaveChanges                       private bool  disposed           protected virtual void Dispose bool disposing                        if    disposed                                if  disposing                                         context Dispose                                                 disposed   true                     public void Dispose                         Dispose true               GC SuppressFinalize this                       Startup cs  relevant code   public void ConfigureServices IServiceCollection services           Add framework services      services AddDbContext lt BloggingContext gt  options   gt          options UseSqlServer Configuration GetConnectionString  DefaultConnection           services AddScoped lt IBloggerRepository  BloggerRepository gt          services AddMvc            Add application services      services AddTransient lt IEmailSender  AuthMessageSender gt         services AddTransient lt ISmsSender  AuthMessageSender gt         Controller  BlogController cs   using System Linq  using Microsoft AspNetCore Mvc  using WebApplication1 Data  using WebApplication1 Models   namespace WebApplication1 Controllers       public class BlogController   Controller               private readonly IBloggerRepository  repository           public BlogController BloggerRepository repository                         repository   repository                     public IActionResult Index                         return View  repository GetBlogs   ToList                        public IActionResult Create                         return View                        HttpPost           ValidateAntiForgeryToken          public IActionResult Create Blog blog                        if  ModelState IsValid                                 repository InsertBlog blog                    repository Save                    return RedirectToAction  Index                              return View blog                       I m not sure what I m doing wrong  Any ideas

User · Answer

I got this error because I declared a variable (above the ConfigureServices method) of type that was my context. I had:

CupcakeContext _ctx

Not sure what I was thinking. I know it's legal to do this if your passing in a parameter to the Configure method.

User · Answer

This issue is because you didn t register the data access component with the interface written for it  Try using as follows  services AddTransient lt IMyDataProvider  MyDataAccess gt

User · Answer

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 lt IBloggerRepository  BloggerRepository gt      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

User · Answer

I got this issue because of a rather silly mistake  I had forgotten to hook my service configuration procedure to discover controllers automatically in the ASP NET Core application   Adding this method solved it      Add framework services              services AddMvc                        AddControllersAsServices             lt ---- Super important

User · Answer

I had problems trying to inject from my Program cs file  by using the CreateDefaultBuilder like below  but ended up solving it by skipping the default binder   see below   var host   Host CreateDefaultBuilder args   ConfigureWebHostDefaults webBuilder   gt        webBuilder ConfigureServices servicesCollection   gt    servicesCollection AddSingleton lt ITest gt  x   gt  new Test             webBuilder UseStartup lt Startup gt        Build     It seems like the Build should have been done inside of ConfigureWebHostDefaults to get it work  since otherwise the configuration will be skipped  but correct me if I am wrong  This approach worked fine  var host   new WebHostBuilder    ConfigureServices servicesCollection   gt        var serviceProvider   servicesCollection BuildServiceProvider        IConfiguration configuration    IConfiguration serviceProvider GetService typeof IConfiguration        servicesCollection AddSingleton lt ISendEmailHandler gt  new SendEmailHandler configuration        UseStartup lt Startup gt     Build     This also shows how to inject an already predefined dependency in  net core  IConfiguration  from

User · Answer

Add services AddSingleton    in your ConfigureServices method of Startup cs file of your project   public void ConfigureServices IServiceCollection services                services AddRazorPages               To register interface with its concrite type         services AddSingleton lt IEmployee  EmployeesMockup gt             For More details please visit this URL   https   www youtube com watch v aMjiiWtfj2M  for All methods  i e  AddSingleton vs AddScoped vs AddTransient  Please visit this URL  https   www youtube com watch v v6Nr7Zman Y amp list PL6n9fhu94yhVkdrusLaQsfERmL Jh4XmU amp index 44

User · Answer

In my case I was trying to do dependency injection for an object which required constructor arguments  In this case  during Startup I just provided the arguments from the configuration file  for example   var config   Configuration GetSection  subservice   Get lt SubServiceConfig gt     services AddScoped lt ISubService gt  provider   gt  new SubService config value1  config value2

User · Answer

I was getting below exception          System InvalidOperationException  Unable to resolve service for type  System Func 1 IBlogContext            while attempting to activate  BlogContextFactory   r n at          Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory CreateArgumentCallSites Type serviceType  Type implementationType  ISet 1 callSiteChain  ParameterInfo   parameters  Boolean throwIfCallSiteNotFound  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory CreateConstructorCallSite Type serviceType  Type implementationType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory TryCreateExact ServiceDescriptor descriptor  Type serviceType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory TryCreateExact Type serviceType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory CreateCallSite Type serviceType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory CreateArgumentCallSites Type serviceType  Type implementationType  ISet 1 callSiteChain  ParameterInfo   parameters  Boolean throwIfCallSiteNotFound  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory CreateConstructorCallSite Type serviceType  Type implementationType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory TryCreateExact ServiceDescriptor descriptor  Type serviceType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory TryCreateExact Type serviceType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceLookup CallSiteFactory CreateCallSite Type serviceType  ISet 1 callSiteChain  r n at Microsoft Extensions DependencyInjection ServiceProvider CreateServiceAccessor Type serviceType  ServiceProvider serviceProvider  r n at System Collections Concurrent ConcurrentDictionaryExtensions GetOrAdd TKey  TValue  TArg   ConcurrentDictionary 2 dictionary  TKey key  Func 3 valueFactory  TArg arg  r n at Microsoft Extensions DependencyInjection ServiceProvider GetService Type serviceType  r n at Microsoft Extensions Internal ActivatorUtilities GetService IServiceProvider sp  Type type  Type requiredBy  Boolean isDefaultParameterRequired  r n at lambda method Closure   IServiceProvider   Object     r n at Microsoft AspNetCore Mvc Controllers ControllerFactoryProvider  lt  gt c  DisplayClass5 0  lt CreateControllerFactory gt g  CreateController 0 ControllerContext controllerContext  r n at Microsoft AspNetCore Mvc Internal ControllerActionInvoker Next State amp  next  Scope amp  scope  Object amp  state  Boolean amp  isCompleted  r n at Microsoft AspNetCore Mvc Internal ControllerActionInvoker InvokeInnerFilterAsync   r n at Microsoft AspNetCore Mvc Internal ResourceInvoker InvokeNextExceptionFilterAsync     Because I wanted register Factory to create instances of DbContext Derived class IBlogContextFactory and use Create method to instantiate instance of Blog Context so that I can use below pattern along with dependency Injection and can also use mocking for unit testing   the pattern I wanted to use is   public async Task lt List lt Blog gt  gt  GetBlogsAsync                         using  var context   new BloggingContext                                  return await context Blogs ToListAsync                              But Instead of new BloggingContext   I want to Inject factory via constructor as in below BlogController class       Route  blogs api v1     public class BlogController   ControllerBase       IBloggingContextFactory  bloggingContextFactory       public BlogController IBloggingContextFactory bloggingContextFactory                 bloggingContextFactory   bloggingContextFactory              HttpGet  blog  id         public async Task lt Blog gt  Get int id                  validation goes here          Blog blog   null             Instantiage context only if needed and dispose immediately         using  IBloggingContext context    bloggingContextFactory CreateContext                          blog   await context Blogs FindAsync id                       Do further processing without need of context          return blog            here is my service registration code               services              AddDbContext lt BloggingContext gt                 AddTransient lt IBloggingContext  BloggingContext gt                 AddTransient lt IBloggingContextFactory  BloggingContextFactory gt       and below are my models and factory classes      public interface IBloggingContext   IDisposable       DbSet lt Blog gt  Blogs   get  set        DbSet lt Post gt  Posts   get  set       public class BloggingContext   DbContext  IBloggingContext       public DbSet lt Blog gt  Blogs   get  set        public DbSet lt Post gt  Posts   get  set         protected override void OnConfiguring DbContextOptionsBuilder optionsBuilder                optionsBuilder UseInMemoryDatabase  blogging db              optionsBuilder UseSqlite  Data Source blogging db             public interface IBloggingContextFactory       IBloggingContext CreateContext       public class BloggingContextFactory   IBloggingContextFactory       private Func lt IBloggingContext gt   contextCreator      public BloggingContextFactory Func lt IBloggingContext gt  contextCreator    This is fine with  net and unity  this is treated as factory function  but creating problem in  netcore service provider                contextCreator   contextCreator             public IBloggingContext CreateContext                 return  contextCreator             public class Blog       public Blog                 CreatedAt   DateTime Now             public Blog int id  string url  string deletedBy    this                 BlogId   id          Url   url          DeletedBy   deletedBy          if   string IsNullOrWhiteSpace deletedBy                         DeletedAt   DateTime Now                      public int BlogId   get  set        public string Url   get  set        public DateTime CreatedAt   get  set        public DateTime  DeletedAt   get  set        public string DeletedBy   get  set        public ICollection lt Post gt  Posts   get  set         public override string ToString                 return   id  BlogId    Url  Url    CreatedAt    CreatedAt   DeletedBy    DeletedBy   DeletedAt   DeletedAt             public class Post       public int PostId   get  set        public string Title   get  set        public string Content   get  set        public int BlogId   get  set        public Blog Blog   get  set        ----- To Fix this in  net Core MVC project -- I did below changes on dependency registration              services              AddDbContext lt BloggingContext gt                 AddTransient lt IBloggingContext  BloggingContext gt                 AddTransient lt IBloggingContextFactory  BloggingContextFactory gt                       sp   gt  new BloggingContextFactory       gt  sp GetService lt IBloggingContext gt                          In short in  net core developer is responsible to inject factory function  which in case of Unity and  Net Framework was taken care of

User · Answer

I replaced    services Add new ServiceDescriptor typeof IMyLogger   typeof MyLogger       With    services AddTransient lt IMyLogger  MyLogger gt       And it worked for me

User · Answer

If you are using AutoFac and getting this error  you should add an  As  statement to specify the service that the concrete implementation implements   Ie  you should write   containerBuilder RegisterType lt DataService gt    As lt DataService gt       instead of  containerBuilder RegisterType lt DataService gt

User · Answer

You need to add a new service for DBcontext in the startup   Default  services AddDbContext lt ApplicationDbContext gt  options   gt                  options UseSqlServer                      Configuration GetConnectionString  DefaultConnection        Add this  services AddDbContext lt NewDBContext gt  options   gt                  options UseSqlServer                      Configuration GetConnectionString  NewConnection

User · Answer

Public void ConfigureServices IServiceCollection services        services AddScoped lt IEventRepository  EventRepository gt                    You forgot to add  services AddScoped  in startup ConfigureServices method

User · Answer

Change BloggerRepository to IBloggerRepository

User · Answer

I was having a different problem  and yeah the parameterized constructor  for my controller was already added with the correct interface  What I did was something straightforward  I just go to my startup cs file  where I could see a call to register method   public void ConfigureServices IServiceCollection services       services Register        In my case  this Register method was in a separate class Injector  So I had to add my newly introduced Interfaces there    public static class Injector       public static void Register this IServiceCollection services                services AddTransient lt IUserService  UserService gt             services AddTransient lt IUserDataService  UserDataService gt               If you see  the parameter to this function is this IServiceCollection  Hope this helps

User · Answer

I ran into this issue because in the dependency injection setup I was missing a dependency of a repository that is a dependency of a controller   services AddScoped lt IDependencyOne  DependencyOne gt         lt -- I was missing this line  services AddScoped lt IDependencyTwoThatIsDependentOnDependencyOne  DependencyTwoThatIsDependentOnDependencyOne gt

User · Answer

I had the same issue and found out that my code was using the injection before it was initialized   services AddControllers       Will cause a problem if you use your IBloggerRepository in there since it s defined after this line  services AddScoped lt IBloggerRepository  BloggerRepository gt       I know it has nothing to do with the question  but since I was sent to this page  I figure out it my be useful to someone else

User · Answer

Resolving a service is done even before the class code is reached  so we need to check our dependency injections    In my case I added          services AddScoped lt IMeasurementService  MeasurementService gt       in StartupExtensions cs

User · Answer

ohh  Thank  kimbaudi  i followed this tuts  https   dotnettutorials net lesson generic-repository-pattern-csharp-mvc   and got the same error as your  But after read your code i found out my solution was adding      services AddScoped IGenericRepository  GenericRepository     into ConfigureServices method in StartUp cs file

User · Answer

You might be missing this  services AddScoped lt IDependencyTwoThatIsDependentOnDependencyOne  DependencyTwoThatIsDependentOnDependencyOne gt

User · Answer

In my case   Net Core 3 0 API in Startup cs  in method public void ConfigureServices IServiceCollection services   I had to add services AddScoped lt IStateService  StateService gt

User · Answer

Only if anyone have the same situation like me  I am doing a tutorial of EntityFramework with existing database  but when the new database context is created on the models folders  we need to update the context in the startup  but not only in services AddDbContext but AddIdentity too if you have users authentication        services AddDbContext lt NewDBContext gt  options   gt                  options UseSqlServer Configuration GetConnectionString  DefaultConnection       services AddIdentity lt ApplicationUser  IdentityRole gt                     AddEntityFrameworkStores lt NewDBContext gt                     AddDefaultTokenProviders

User · Answer

I had to add this line in the ConfigureServices in order to work   services AddSingleton lt IOrderService  OrderService gt

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

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