Error when specifying a HttpMessageHandler - System.InvalidOperationException : No service for type 'RetryDelegatingHandler' has been registered.

I created a custom HttpMessageHandler to handle the retry logic in my HttpClient. (I know that I could have used Polly but what is the fun in that?)

I registered the HttpMessageHandler as part of my typed http client like this:

	services.AddHttpClient<IGitHubService, GitHubService>(httpClient =>
	{
	httpClient.BaseAddress = new Uri("https://api.github.com/");
	httpClient.AddHttpMessageHandler<RetryDelegatingHandler>();
	// ...
	});

view raw Startup.cs hosted with ❤ by GitHub

However when I ran my application it failed with the following error:

System.InvalidOperationException : No service for type ‘Reliability.RetryDelegatingHandler' has been registered.

  Stack Trace:

ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)

ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)

<>c__4`1.<AddHttpMessageHandler>b__4_1(HttpMessageHandlerBuilder b)

<>c__DisplayClass17_0.<CreateHandlerEntry>g__Configure|0(HttpMessageHandlerBuilder b)

<>c__DisplayClass3_0.<Configure>b__0(HttpMessageHandlerBuilder builder)

DefaultHttpClientFactory.CreateHandlerEntry(String name)

<.ctor>b__1()

Lazy`1.ViaFactory(LazyThreadSafetyMode mode)

Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)

Lazy`1.CreateValue()

<7 more frames...>

CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)

CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)

CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)

<>c__DisplayClass2_0.<RealizeService>b__0(ServiceProviderEngineScope scope)

ServiceProvider.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)

ServiceProvider.GetService(Type serviceType)

ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)

ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)

To use the generic AddHttpMessageHandler<T> I need to register the handler through the IoC container:

services.AddTransient<RetryDelegatingHandler>();

view raw RegisterHandler.cs hosted with ❤ by GitHub

As an alternative I can use another overload and instantiate the handler myself:

	services.AddHttpClient<IGitHubService, GitHubService>(httpClient =>
	{
	httpClient.BaseAddress = new Uri("https://api.github.com/");
	httpClient.AddHttpMessageHandler(s=> new RetryDelegatingHandler());
	// ...
	});

view raw Startup.cs hosted with ❤ by GitHub