NSwag: System.InvalidOperationException: Unable to resolve service for type 'Microsoft.Extensions.Configuration.IConfiguration' while attempting to activate 'Startup'

Hi NSwag team,

Before this issue is marked as duplicate, I want to tell that I have already gone through 2641 and 1920 and nothing mentioned there worked for me. Also please note that I had to add all of the following files which is why the question looks so big in itself. Sorry about that.

I am using NSwagStudio to generate the client for my API. NSwag version: 13.6.2.0 Runtime: .Net Core 3.1

I tried both methods i.e using the assembly and using the .csproj but both didn’t work.

Here are the project details.

.csproj <PropertyGroup> <TargetFramework>netcoreapp3.1</TargetFramework> <AssemblyName>MyProject.Comm.Api</AssemblyName> <RootNamespace>MyProject.Comm.Api</RootNamespace> <LangVersion>latest</LangVersion> <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies> <ServerGarbageCollection>false</ServerGarbageCollection> <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel> <PreserveCompilationContext>true</PreserveCompilationContext> <MvcRazorExcludeRefAssembliesFromPublish>false</MvcRazorExcludeRefAssembliesFromPublish> <StartupObject>MyProject.Comm.Api.Program</StartupObject> </PropertyGroup>

.NSwag

{
  "runtime": "NetCore31",
  "defaultVariables": null,
  "documentGenerator": {
    "aspNetCoreToOpenApi": {
      "project": "",
      "msBuildProjectExtensionsPath": null,
      "configuration": null,
      "runtime": null,
      "targetFramework": null,
      "noBuild": true,
      "verbose": false,
      "workingDirectory": null,
      "requireParametersWithoutDefault": false,
      "apiGroupNames": null,
      "defaultPropertyNameHandling": "Default",
      "defaultReferenceTypeNullHandling": "Null",
      "defaultDictionaryValueReferenceTypeNullHandling": "NotNull",
      "defaultResponseReferenceTypeNullHandling": "NotNull",
      "defaultEnumHandling": "Integer",
      "flattenInheritanceHierarchy": false,
      "generateKnownTypes": true,
      "generateEnumMappingDescription": false,
      "generateXmlObjects": false,
      "generateAbstractProperties": false,
      "generateAbstractSchemas": true,
      "ignoreObsoleteProperties": false,
      "allowReferencesWithProperties": false,
      "excludedTypeNames": [],
      "serviceHost": null,
      "serviceBasePath": null,
      "serviceSchemes": [],
      "infoTitle": "My Title",
      "infoDescription": null,
      "infoVersion": "1.0.0",
      "documentTemplate": null,
      "documentProcessorTypes": [],
      "operationProcessorTypes": [],
      "typeNameGeneratorType": null,
      "schemaNameGeneratorType": null,
      "contractResolverType": null,
      "serializerSettingsType": null,
      "useDocumentProvider": false,
      "documentName": "v1",
      "aspNetCoreEnvironment": null,
      "createWebHostBuilderMethod": null,
      "startupType": null,
      "allowNullableBodyParameters": true,
      "output": null,
      "outputType": "Swagger2",
      "newLineBehavior": "Auto",
      "assemblyPaths": [
        "../bin/Debug/netcoreapp3.1/MyProject.Comm.Api.dll"
      ],
      "assemblyConfig": null,
      "referencePaths": [],
      "useNuGetCache": false
    }
  },
  "codeGenerators": {
    "openApiToCSharpClient": {
      "clientBaseClass": null,
      "configurationClass": null,
      "generateClientClasses": true,
      "generateClientInterfaces": true,
      "clientBaseInterface": null,
      "injectHttpClient": true,
      "disposeHttpClient": true,
      "protectedMethods": [],
      "generateExceptionClasses": true,
      "exceptionClass": "ApiException",
      "wrapDtoExceptions": true,
      "useHttpClientCreationMethod": false,
      "httpClientType": "System.Net.Http.HttpClient",
      "useHttpRequestMessageCreationMethod": false,
      "useBaseUrl": false,
      "generateBaseUrlProperty": true,
      "generateSyncMethods": false,
      "exposeJsonSerializerSettings": false,
      "clientClassAccessModifier": "public",
      "typeAccessModifier": "public",
      "generateContractsOutput": false,
      "contractsNamespace": null,
      "contractsOutputFilePath": null,
      "parameterDateTimeFormat": "s",
      "parameterDateFormat": "yyyy-MM-dd",
      "generateUpdateJsonSerializerSettingsMethod": true,
      "useRequestAndResponseSerializationSettings": false,
      "serializeTypeInformation": false,
      "queryNullValue": "",
      "className": "{controller}ApiClient",
      "operationGenerationMode": "MultipleClientsFromOperationId",
      "additionalNamespaceUsages": [],
      "additionalContractNamespaceUsages": [],
      "generateOptionalParameters": false,
      "generateJsonMethods": false,
      "enforceFlagEnums": false,
      "parameterArrayType": "System.Collections.Generic.IEnumerable",
      "parameterDictionaryType": "System.Collections.Generic.IDictionary",
      "responseArrayType": "System.Collections.Generic.ICollection",
      "responseDictionaryType": "System.Collections.Generic.IDictionary",
      "wrapResponses": false,
      "wrapResponseMethods": [],
      "generateResponseClasses": true,
      "responseClass": "SwaggerResponse",
      "namespace": "MyProject.Gateway.Api.Clients.CommApi",
      "requiredPropertiesMustBeDefined": true,
      "dateType": "System.DateTimeOffset",
      "jsonConverters": null,
      "anyType": "object",
      "dateTimeType": "System.DateTimeOffset",
      "timeType": "System.TimeSpan",
      "timeSpanType": "System.TimeSpan",
      "arrayType": "System.Collections.Generic.ICollection",
      "arrayInstanceType": "System.Collections.ObjectModel.Collection",
      "dictionaryType": "System.Collections.Generic.IDictionary",
      "dictionaryInstanceType": "System.Collections.Generic.Dictionary",
      "arrayBaseType": "System.Collections.ObjectModel.Collection",
      "dictionaryBaseType": "System.Collections.Generic.Dictionary",
      "classStyle": "Poco",
      "generateDefaultValues": true,
      "generateDataAnnotations": true,
      "excludedTypeNames": [],
      "excludedParameterNames": [],
      "handleReferences": false,
      "generateImmutableArrayProperties": false,
      "generateImmutableDictionaryProperties": false,
      "jsonSerializerSettingsTransformationMethod": null,
      "inlineNamedArrays": false,
      "inlineNamedDictionaries": false,
      "inlineNamedTuples": true,
      "inlineNamedAny": false,
      "generateDtoTypes": true,
      "generateOptionalPropertiesAsNullable": false,
      "generateNullableReferenceTypes": false,
      "templateDirectory": null,
      "typeNameGeneratorType": null,
      "propertyNameGeneratorType": null,
      "enumNameGeneratorType": null,
      "serviceHost": null,
      "serviceSchemes": null,
      "output": null,
      "newLineBehavior": "Auto"
    }
  }
}

When I now try to generate client for my API I get the following issue.

System.InvalidOperationException: Unable to resolve service for type 'Microsoft.Extensions.Configuration.IConfiguration' while attempting to activate 'MyProject.Comm.Api.Startup'.

Runtime: NetCore31
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters)
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetServiceOrCreateInstance(IServiceProvider provider, Type type)
   at Microsoft.AspNetCore.Hosting.StartupLoader.LoadMethods(IServiceProvider hostingServiceProvider, Type startupType, String environmentName)
   at Microsoft.AspNetCore.Hosting.WebHostBuilderExtensions.<>c__DisplayClass3_0.<UseStartup>b__1(IServiceProvider sp)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider)
   at Microsoft.AspNetCore.Hosting.WebHost.EnsureStartup()
   at Microsoft.AspNetCore.Hosting.WebHost.EnsureApplicationServices()
   at Microsoft.AspNetCore.Hosting.WebHost.Initialize()
   at Microsoft.AspNetCore.Hosting.WebHostBuilder.Build()
   at NSwag.Commands.Generation.OpenApiGeneratorCommandBase`1.CreateWebHostAsync(AssemblyLoader assemblyLoader) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\OpenApiGeneratorCommandBase.cs:line 342
   at NSwag.Commands.Generation.AspNetCore.AspNetCoreToSwaggerCommand.RunIsolatedAsync(AssemblyLoader assemblyLoader) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiCommand.cs:line 310
   at NSwag.Commands.IsolatedCommandBase`1.IsolatedCommandAssemblyLoader`1.Run(String commandType, String commandData, String[] assemblyPaths, String[] referencePaths) in C:\projects\nswag\src\NSwag.Commands\Commands\IsolatedCommandBase.cs:line 76
   at NSwag.Commands.IsolatedCommandBase`1.<>c__DisplayClass17_0.<RunIsolatedAsync>b__0() in C:\projects\nswag\src\NSwag.Commands\Commands\IsolatedCommandBase.cs:line 61
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location where exception was thrown ---
   at NSwag.Commands.IsolatedCommandBase`1.RunIsolatedAsync(String configurationFile) in C:\projects\nswag\src\NSwag.Commands\Commands\IsolatedCommandBase.cs:line 61
   at NSwag.Commands.IsolatedSwaggerOutputCommandBase`1.RunAsync(CommandLineProcessor processor, IConsoleHost host) in C:\projects\nswag\src\NSwag.Commands\Commands\IsolatedSwaggerOutputCommandBase.cs:line 51
   at NSwag.Commands.Generation.AspNetCore.AspNetCoreToSwaggerCommand.RunAsync(CommandLineProcessor processor, IConsoleHost host) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiCommand.cs:line 95
   at NSwag.Commands.NSwagDocumentBase.GenerateSwaggerDocumentAsync() in C:\projects\nswag\src\NSwag.Commands\NSwagDocumentBase.cs:line 280
   at NSwag.Commands.NSwagDocument.ExecuteAsync() in C:\projects\nswag\src\NSwag.Commands\NSwagDocument.cs:line 81
   at NSwag.Commands.Document.ExecuteDocumentCommand.ExecuteDocumentAsync(IConsoleHost host, String filePath) in C:\projects\nswag\src\NSwag.Commands\Commands\Document\ExecuteDocumentCommand.cs:line 86
   at NSwag.Commands.Document.ExecuteDocumentCommand.RunAsync(CommandLineProcessor processor, IConsoleHost host) in C:\projects\nswag\src\NSwag.Commands\Commands\Document\ExecuteDocumentCommand.cs:line 32
   at NConsole.CommandLineProcessor.ProcessSingleAsync(String[] args, Object input)
   at NConsole.CommandLineProcessor.ProcessAsync(String[] args, Object input)
   at NConsole.CommandLineProcessor.Process(String[] args, Object input)
   at NSwag.Commands.NSwagCommandProcessor.Process(String[] args) in C:\projects\nswag\src\NSwag.Commands\NSwagCommandProcessor.cs:line 56

And when I try generating the client using the .csproj file with Nobuild= true, I get the following error

Launcher directory: C:\Program Files (x86)\Rico Suter\NSwagStudio\NetCore31
System.InvalidOperationException: Swagger generation failed with non-zero exit code '1'.

Runtime: NetCore31
   at NSwag.Commands.Generation.AspNetCore.AspNetCoreToSwaggerCommand.RunAsync(CommandLineProcessor processor, IConsoleHost host) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiCommand.cs:line 221
   at NSwag.Commands.NSwagDocumentBase.GenerateSwaggerDocumentAsync() in C:\projects\nswag\src\NSwag.Commands\NSwagDocumentBase.cs:line 280
   at NSwag.Commands.NSwagDocument.ExecuteAsync() in C:\projects\nswag\src\NSwag.Commands\NSwagDocument.cs:line 81
   at NSwag.Commands.Document.ExecuteDocumentCommand.ExecuteDocumentAsync(IConsoleHost host, String filePath) in C:\projects\nswag\src\NSwag.Commands\Commands\Document\ExecuteDocumentCommand.cs:line 86
   at NSwag.Commands.Document.ExecuteDocumentCommand.RunAsync(CommandLineProcessor processor, IConsoleHost host) in C:\projects\nswag\src\NSwag.Commands\Commands\Document\ExecuteDocumentCommand.cs:line 32
   at NConsole.CommandLineProcessor.ProcessSingleAsync(String[] args, Object input)
   at NConsole.CommandLineProcessor.ProcessAsync(String[] args, Object input)
   at NConsole.CommandLineProcessor.Process(String[] args, Object input)
   at NSwag.Commands.NSwagCommandProcessor.Process(String[] args) in C:\projects\nswag\src\NSwag.Commands\NSwagCommandProcessor.cs:line 56

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> System.InvalidOperationException: aspnet2swaggercommand requires the entry point type.MyProject.Comm.Api.Program to have either an BuildWebHost or CreateWebHostBuilder/CreateHostBuilder method. See https://docs.microsoft.com/en-us/aspnet/core/fundamentals/hosting?tabs=aspnetcore2x for suggestions on ways to refactor your startup type.
   at NSwag.Commands.Generation.AspNetCore.AspNetCoreToOpenApiGeneratorCommandEntryPoint.GetServiceProvider(String applicationName) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiGeneratorCommandEntryPoint.cs:line 93
   at NSwag.Commands.Generation.AspNetCore.AspNetCoreToOpenApiGeneratorCommandEntryPoint.Process(String commandContent, String outputFile, String applicationName) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiGeneratorCommandEntryPoint.cs:line 26
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
   at NSwag.AspNetCore.Launcher.Program.Main(String[] args) in C:\projects\nswag\src\NSwag.AspNetCore.Launcher\Program.cs:line 170

These errors refer to the Startup.cs and Program.cs files so here are those two files.

Program.cs

using System;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using MyProject.Logging;

namespace MyProject.Comm.Api
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Console.Title = "MyProject.CommApi";
            BuildWebHost(args).RunWithLogging();
          
        }

        private static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseMyProjectLogging<Startup>("MyProject.CommApi", Environment.GetEnvironmentVariable("ApplicationInsights__InstrumentationKey"))
                .Build();
    }
}

Startup.cs

using Data.LinqToDb;
using MyProject.BaseApi;
using MyProject.Comm.Api.Constants;
using MyProject.Comm.Api.Extensions;
using MyProject.Configurations;
using MyProject.EmailService;
using MyProject.EmailService.Configuration;
using MyProject.Twilio;
using JetBrains.Annotations;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc.ApiExplorer;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System;
using System.Reflection;

namespace MyProject.Comm.Api
{
    public class Startup
    {
        private readonly ILogger<Startup> _logger;
        private readonly ILoggerFactory _loggerFactory;

        [UsedImplicitly]
        public Startup(
            [NotNull] IConfiguration configuration,
            [NotNull] IWebHostEnvironment env, 
            [NotNull] ILoggerFactory loggerFactory,
            [NotNull] ILogger<Startup> logger)
        {
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
            _loggerFactory = loggerFactory ?? throw new ArgumentNullException(nameof(loggerFactory));
            Configuration = configuration ?? throw new ArgumentNullException(nameof(configuration));
            Environment = env ?? throw new ArgumentNullException(nameof(env));
        }

        private IConfiguration Configuration { get; }
        private IWebHostEnvironment Environment { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            var subsystemName = typeof(Startup).GetTypeInfo().Assembly.GetName().Name;

            services.AddAppSettings(Configuration);
            var serviceBusSettings = new ServiceBus.ServiceBusSettings();
            Configuration.GetSection("ServiceBus").Bind(serviceBusSettings);

            services.AddMyProjectSecureApi(subsystemName, Configuration, serviceBusSettings, _logger, _loggerFactory, Environment);

            var emailSettings = new EmailSettings();
            Configuration.GetSection("SmtpSettings").Bind(emailSettings);
            emailSettings.DefaultFromAddress = Configuration["EmailAddresses:DefaultFromAddress"];
            services.AddEmailService(emailSettings);

            services.AddRazorTemplateParser("\\MessageTemplates", Configuration);

            var twilioSettings = new Twilio.Configuration.Twilio();
            Configuration.GetSection("Twilio").Bind(twilioSettings);
            services.AddTwilio(twilioSettings);

            var dbConnectionString = Configuration.GetSection("Linq2DbConnectionSettings:ConnectionString").Value;
            services.ConfigureDbUp(dbConnectionString, Environment);
            services.ConfigureLinqToDb<IDataContext, DatabaseContext>(Configuration, Environment);
            services.RegisterRepositories();

        }

        

        [UsedImplicitly]
        public void Configure(IApplicationBuilder app, IServiceProvider serviceProvider, IApiVersionDescriptionProvider provider)
        {
            app.UseCors(AppConstants.AllowedOrigins);
            app.UseMyProjectSecureApi(Environment, Configuration, serviceProvider, true, provider);
        }
    }
}

Any help in this would be highly appreciated. Thanks a lot! Regards