BUG: BFF v4 + EF + Blazor: Cannot resolve scoped service SessionDbContext from root provider.

[ajtowf]

I've created this repo to reproduce the problem: https://github.com/ajtowf/BlazorBffApp

It's the official sample for v3 and blazor, upgraded to latest v4 RC, just added the EF part.

And the following is logged:

fail: Microsoft.Extensions.Hosting.Internal.Host[11]
      Hosting failed to start
      System.InvalidOperationException: Cannot resolve scoped service 'Duende.Bff.EntityFramework.SessionDbContext' from root provider.
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteValidator.ValidateResolution(ServiceCallSite callSite, IServiceScope scope, IServiceScope rootScope)
         at Microsoft.Extensions.DependencyInjection.ServiceProvider.OnResolve(ServiceCallSite callSite, IServiceScope scope)
         at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(ServiceIdentifier serviceIdentifier, ServiceProviderEngineScope serviceProviderEngineScope)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
         at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
         at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
         at Duende.Bff.EntityFramework.BffBuilderExtensions.<>c__4`2.<AddEntityFrameworkServerSideSessionsServices>b__4_0(IServiceProvider svcs) in /_/bff/src/Bff.EntityFramework/BffBuilderExtensions.cs:line 80
         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.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite callSite, 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.ServiceProvider.CreateServiceAccessor(ServiceIdentifier serviceIdentifier)
         at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
         at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(ServiceIdentifier serviceIdentifier, ServiceProviderEngineScope serviceProviderEngineScope)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
         at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
         at Microsoft.Extensions.DependencyInjection.AutoActivationHostedService.StartAsync(CancellationToken cancellationToken)
         at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>b__14_1(IHostedService service, CancellationToken token)
         at Microsoft.Extensions.Hosting.Internal.Host.ForeachService[T](IEnumerable`1 services, CancellationToken token, Boolean concurrent, Boolean abortOnFirstException, List`1 exceptions, Func`3 operation)

[Erwinvandervalk]

Thank you for reporting this. We're looking into it.

[ajtowf]

Here's a feature branch to re-produce: https://github.com/ajtowf/BlazorBffApp/tree/feature/v4

Quick question, is there anyone using BFF + EF + Blazor (besides us) ? This really feels like the most basic scenario.

[Erwinvandervalk]

We're raising a PR for this issue, which hopefully will be released soon.
DuendeSoftware/products#2262

There's also a workaround. If you turn off scope validation in the service provider, the error goes away.

hostBuilder.Host.UseDefaultServiceProvider(opt => opt.ValidateScopes = false);

[ajtowf]

Thanks, now I only run into this bug DuendeSoftware/products#2251, seems like this isn't fixed with RC3?

[Erwinvandervalk]

You're correct. So far, that fix has only been released for the 3.x branch. The fix for V4 is scheduled for the next (and hopefully last) V4 RC, which is due to be released very soon and will be targeting .net 10 final.