.NET 9 + OpenAPI: InvalidOperationException - cannot resolve IOptionsSnapshot from root provider

[johncrim]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

This issue is touched on here: #58805, thought it takes a while to get to it. There could be multiple issues discussed there. Most importantly, the problem has not been fixed for .NET 9.

This change: cf0b8a5

Needs to be backported to .NET 9. As you can see here, OpenApi 9.0.15 still uses IOptionsSnapshot instead of IOptionsMonitor.
https://github.com/dotnet/aspnetcore/blame/v9.0.15/src/OpenApi/src/Services/OpenApiDocumentProvider.cs

This bug is not logged or reported to the user, it just results in an error when reading an OpenAPI doc (to write to a file).

Expected Behavior

IDocumentProvider.GenerateAsync() can be called outside of a request scoped ServiceProvider.

Steps To Reproduce

The test cases described in #58805 should still reproduce the bug.

Exceptions (if any)

Call stacks:

System.InvalidOperationException
  HResult=0x80131509
  Message=Cannot resolve scoped service 'Microsoft.Extensions.Options.IOptionsSnapshot`1[Microsoft.AspNetCore.OpenApi.OpenApiOptions]' from root provider.
  Source=Microsoft.Extensions.DependencyInjection
  StackTrace:
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteValidator.ValidateResolution(ServiceCallSite callSite, IServiceScope scope, IServiceScope rootScope) in /_/src/runtime/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/CallSiteValidator.cs:line 26

[System.InvalidOperationException thrown]
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteValidator.ValidateResolution(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceCallSite callSite, Microsoft.Extensions.DependencyInjection.IServiceScope scope, Microsoft.Extensions.DependencyInjection.IServiceScope rootScope) Line 26
	at /_/src/runtime/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/CallSiteValidator.cs(26)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceProvider.OnResolve(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceCallSite callSite, Microsoft.Extensions.DependencyInjection.IServiceScope scope) Line 203
	at /_/src/runtime/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceProvider.cs(203)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceIdentifier serviceIdentifier, Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope serviceProviderEngineScope) Line 212
	at /_/src/runtime/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceProvider.cs(212)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(System.Type serviceType) Line 50
	at /_/src/runtime/src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/ServiceProviderEngineScope.cs(50)
Microsoft.Extensions.DependencyInjection.Abstractions.dll!Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(System.IServiceProvider provider, System.Type serviceType) Line 45
	at /_/src/runtime/src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ServiceProviderServiceExtensions.cs(45)
Microsoft.Extensions.DependencyInjection.Abstractions.dll!Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService<Microsoft.Extensions.Options.IOptionsSnapshot<Microsoft.AspNetCore.OpenApi.OpenApiOptions>>(System.IServiceProvider provider) Line 65
	at /_/src/runtime/src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ServiceProviderServiceExtensions.cs(65)
Microsoft.AspNetCore.OpenApi.dll!Microsoft.Extensions.ApiDescriptions.OpenApiDocumentProvider.GenerateAsync(string documentName, System.IO.TextWriter writer)
[Lightweight Function]
System.Private.CoreLib.dll!System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, object[] parameters, System.Globalization.CultureInfo culture)
Microsoft.WebTools.ApiEndpointDiscovery.dll!Microsoft.WebTools.ApiEndpointDiscovery.OpenApiDocumentGenerator.InvokeMethod(System.Reflection.MethodInfo method, object instance, object[] arguments)
Microsoft.WebTools.ApiEndpointDiscovery.dll!Microsoft.WebTools.ApiEndpointDiscovery.OpenApiDocumentGenerator.WriteOpenApiDocumentAsync(string docGenDirectory, string projectName, string documentName, System.Reflection.MethodInfo generateMethod, object service)
Microsoft.WebTools.ApiEndpointDiscovery.dll!Microsoft.WebTools.ApiEndpointDiscovery.OpenApiDocumentGenerator.GenerateOpenApiDocumentsAsync(string outputDirectory, string projectName, System.IServiceProvider services, System.Threading.CancellationToken cancelToken)
Microsoft.WebTools.ApiEndpointDiscovery.dll!Microsoft.WebTools.ApiEndpointDiscovery.HostingStartup.Configure.AnonymousMethod__1()
[Resuming Async Method]

.NET Version

9.0.305

Anything else?

Microsoft.AspNetCore.App 9.0.15
Microsoft.AspNetCore.OpenApi 9.0.15

[github-actions]

Triage Summary

Area: area-minimal — Issue is in OpenApiDocumentProvider (src/OpenApi/, Microsoft.AspNetCore.OpenApi), which falls under the minimal APIs / OpenAPI document generation area.

Type: bug — A clear, reproducible exception (InvalidOperationException: Cannot resolve scoped service IOptionsSnapshot from root provider) occurs when OpenApiDocumentProvider.GenerateAsync() is called outside of a request-scoped ServiceProvider. The fix (switching from IOptionsSnapshot to IOptionsMonitor) was already applied to the main branch but was not backported to .NET 9.

Regression Info

• Previously working version: .NET 10 / main branch (fix applied via commit cf0b8a57)
• Broken since: Still broken in ASP.NET Core 9.0.15 (not backported)
• The fix that resolves the scoped-service-from-root-provider error was applied to main but the .NET 9 branch still uses IOptionsSnapshot in OpenApiDocumentProvider, causing the exception when called from a non-request context (e.g., design-time OpenAPI doc generation via Microsoft.WebTools.ApiEndpointDiscovery).

Potential Duplicates

• .NET 9 - OpenAPI Not Generating Output #58805 — ".NET 9 - OpenAPI Not Generating Output" (similarity: high — same root cause; this is the original issue that the fix was applied for; now closed as completed, but the fix wasn't backported to .NET 9 servicing)

Notes

• The reporter explicitly identifies the missing backport of commit cf0b8a57c248fbdddb5d24a9b8e3018a455efd05 to the .NET 9 branch as the fix needed. This is a servicing/backport request for .NET 9.
• The issue is triggered specifically when tools like Visual Studio's API endpoint discovery call GenerateAsync() outside of an HTTP request context (i.e., from the root IServiceProvider).

Generated by Issue Triage Agent for dotnet/aspnetcore for issue #66470 · ● 274.1K · ◷

[johncrim]

The source of the call is here:

internal sealed class HostingStartup : IHostingStartup, IStartupFilter
{
	private string? _apiDiscoverFilePath;

	public void Configure(IWebHostBuilder builder)
	{
		_apiDiscoverFilePath = Environment.GetEnvironmentVariable("APIDISCOVERY_FILEPATH");
		if (!string.IsNullOrEmpty(_apiDiscoverFilePath))
		{
			builder.ConfigureServices(delegate(IServiceCollection services)
			{
				services.AddEndpointsApiExplorer();
				services.TryAddEnumerable(ServiceDescriptor.Singleton((IStartupFilter)this));
			});
		}
	}

	public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
	{
		return delegate(IApplicationBuilder app)
		{
			IHostApplicationLifetime lifetime = app.ApplicationServices.GetService<IHostApplicationLifetime>();
			lifetime?.ApplicationStarted.Register(async delegate
			{
				await ApplicationEndpointWriter.WriteEndpointsAsync(_apiDiscoverFilePath, app.ApplicationServices, lifetime.ApplicationStopping);
				string directoryName = Path.GetDirectoryName(_apiDiscoverFilePath);
				if (directoryName != null)
				{
					string environmentVariable = Environment.GetEnvironmentVariable("APIDISCOVERY_ProjectName");
					if (environmentVariable != null)
					{
						directoryName = Path.Combine(directoryName, "EndpointInfo");
👉 						await OpenApiDocumentGenerator.GenerateOpenApiDocumentsAsync(directoryName, environmentVariable, app.ApplicationServices, lifetime.ApplicationStopping);  
					}
					else
					{
						Logger.Log("Environment variable APIDISCOVERY_ProjectName not specified so OpenApi documents are not going to be generated");
					}
				}
			});
			next(app);
		};
	}
}