MGCB error, custom ContentTypeSerializer

Hello everybody! I made a custom serializer. The Serialize Realtime method works correctly. However, if I insert this XML into MGCB, I get a strange error. Yes, I have a NuGet package of the Aether project in my project.Physics2D, but it does not participate in XmlSerializer. Can you tell me why I’m getting this error?

public class AssetTypeSerialize<T> : ContentTypeSerializer<T>
        where T : Asset
        protected override T Deserialize(IntermediateReader input, ContentSerializerAttribute format, T existingInstance)
            if (existingInstance == null)
                existingInstance = default(T);

            existingInstance.Name = input.Xml.Name;


            return existingInstance;

        protected override void Serialize(IntermediateWriter output, T value, ContentSerializerAttribute format)

The mgcb does not know of the library. At the bottom of the error message is says that the actual error is FileNotFound.

Select ‘Content’ in the treeview on the top-left, and then in properties add a reference to the Aether.Physics2d assembly/DLL.

One of the libraries that you are using in the Serialization has a reference to Aether.Physics2D and expose one of the aether types as a public property.
… or it uses an aether type as parameter in a public method, etc.

The GetTypes() method tries to resolve the references you have added, including any satellite assemblies.
Therefore you need to have the aether dll next to the dll of the library you have added, or reference the aether.dll separately.

I think you may have to do step 1 and 2 in the picture here, this is a screenshot for one of my projects.

Thank you gentlemens! I did not expect that it would be necessary to connect this library, because the test1.xml not have links to her.