I'm trying to get a bunch of the Microsoft.Extensions.* libraries in Unity and I've found it would work fine in a small quick project, but complains when I started separating them into different folders. It builds, but the editor complains: The above errors do not seem to prevent a successful build, and the build demonstrates the libraries are working successfully. I have found that the editor doesn't report errors if all the assemblies are within the same folder: Above is good! No errors Above is bad, and the editor isn't happy. Both projects produce a build fine, but I'd rather get rid of the errors and enable the assemblies to be nested in their own folder - as I am making them modular through Unity's packages. I have attached a .zip file with both projects. Can I do anything to prevent these errors?