1. Ron Calder
  2. SnapDevelop
  3. Tuesday, 24 March 2020 20:19 PM UTC

I get the following message in the browser when running the WebAPI1 solution.  The app compiles in Snap Develop with no errors.  


InvalidOperationException: Unable to resolve service for type 'WebAPI1.Services.IDepartmentService' while attempting to activate 'WebAPI1.Controllers.SampleController'.

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

  • lambda_method(Closure , IServiceProvider , object[] )

  • Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider+<>c__DisplayClass4_0.<CreateActivator>b__0(ControllerContext controllerContext)

  • Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider+<>c__DisplayClass5_0.<CreateControllerFactory>g__CreateController|0(ControllerContext controllerContext)

  • Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)

  • Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()

  • Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()

  • Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)

  • Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)

  • Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()

  • Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()

  • Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)

  • Microsoft.AspNetCore.ResponseCompression.ResponseCompressionMiddleware.Invoke(HttpContext context)

  • Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Thank you in advance,



Govinda Lopez @Appeon Accepted Answer Pending Moderation
  1. Tuesday, 24 March 2020 21:03 PM UTC
  2. SnapDevelop
  3. # 1

Hi Ron,


I'm not sure what project you are referring to, but try adding the service using the dependency injection. 

services.AddScoped<IDepartmentService, DepartmentService>();

Add this code to your Startup.cs class.


Please let me know if this worked for you.




  1. Ron Calder
  2. Wednesday, 25 March 2020 11:20 AM UTC
That worked!

Thank you so much Govinda!
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