Have you ever encountered the following InvalidOperationException in your .NET solution when using keyed services?

This service descriptor is keyed. Your service provider may not support keyed services.

This exception might be thrown when an IServiceProvider or some code accesses the incorrect properties on an ServiceDescriptor .

Accessing the Correct Properties

To resolve this, Microsoft introduced a range of additional properties that must be accessed instead of their non-keyed ServiceDescriptor counterparts:

• KeyedImplementationFactory over ImplementationFactory
• KeyedImplementationInstance over ImplementationInstnace
• KeyedImplementationType over ImplementationType

To determine which property to access there is an IsKeyedService property which is true when the service has been registered in the IServiceCollection as a keyed service.

var implementationType = service.IsKeyedService ? service.KeyedImplementationType : service.ImplementationType;

Building Keyed Service Providers

If you are a service provider developer, you may need to consider implementing the above and storing the descriptors in a way that allows you to look up by key and service type.

In addition implement the new interface IKeyedServiceProvider and it’s associated methods for retrieving services using a key. Note the key provided is an object type.

interface IKeyedServiceProvider : IServiceProvider
{
    GetKeyedService(Type, Object);
    GetRequiredKeyedService(Type, Object);
}