Replacement for AppDomain.GetLoadedAssemblies() in .NET Core?

What you are looking for is broadly explained here. The author recommends creating a polyfill.

I am going to copy and paste in case the page goes missing.

public class AppDomain
{
    public static AppDomain CurrentDomain { get; private set; }

    static AppDomain()
    {
        CurrentDomain = new AppDomain();
    }

    public Assembly[] GetAssemblies()
    {
        var assemblies = new List<Assembly>();
        var dependencies = DependencyContext.Default.RuntimeLibraries;
        foreach (var library in dependencies)
        {
            if (IsCandidateCompilationLibrary(library))
            {
                var assembly = Assembly.Load(new AssemblyName(library.Name));
                assemblies.Add(assembly);
            }
        }
        return assemblies.ToArray();
    }

    private static bool IsCandidateCompilationLibrary(RuntimeLibrary compilationLibrary)
    {
        return compilationLibrary.Name == ("Specify")
            || compilationLibrary.Dependencies.Any(d => d.Name.StartsWith("Specify"));
    }
}

Fixed this by upgrading my .netstandard projects from 1.4 to 1.6. The package Microsoft.Extensions.DependencyModel 1.1.2 now works.

Edit:

Using .netstandard2.0 removes the need for an AppDomain polyfill class since it contains many more .NET APIs including System.AppDomain