UnityDependencyResolver can't resolve Enum

I work with .Net Framework 4.7 and UnityDependencyResolver. My customer write a constructor with an Enum as the parameter and UnityDependencyResolver cannot initialize this constructor.

I guess the Enum parameter is the cause of the problem. I tried to search using the keyword "UnityDependencyResolver can't resolve Enum", but couldn't find any explanation.

Can someone give me accurate information or a satisfactory explanation? Look forward to the help.

It's been so long ago since I wrote Dependency Injection in .NET that I no longer really remember how this works, but according to it:

Conceptually, it doesn’t always make much sense to register a string or number as a component in a container. However, with Unity this is at least possible.

Consider, as an example, this constructor:

public ChiliConCarne(Spiciness spiciness)

In this example, Spiciness is an enum:

public enum Spiciness
{
    Mild = 0,
    Medium,
    Hot
}

[...]

If you want all consumers of Spiciness to use the same value, you can register Spiciness and ChiliConCarne independently of each other:

container.RegisterInstance(Spiciness.Medium);
container.RegisterType<ICourse, ChiliConCarne>();

When you subsequently resolve ChiliConCarne it will have a Medium Spiciness, as will all other components with a DEPENDENCY on Spiciness.

Have you registered the enum value with the container?