ASP NET Core 2 Cannot find compilation library location for package 'Projectname.Model'

In order asp.net core 2.0 project had successfully found external assemblies .NETStandard2.0, you need to override a built-in MetadataReferenceFeatureProvider. For this we need to add the following class:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection.PortableExecutable;
using Microsoft.AspNetCore.Mvc.ApplicationParts;
using Microsoft.CodeAnalysis;
using Microsoft.Extensions.DependencyModel;

namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
{
    /// <summary>Провайдер нужен для компенсации бага компиляции представлений при подключении сборок .NetStandart2.0</summary>
    public class ReferencesMetadataReferenceFeatureProvider : IApplicationFeatureProvider<MetadataReferenceFeature>
    {
        public void PopulateFeature(IEnumerable<ApplicationPart> parts, MetadataReferenceFeature feature)
        {
            var libraryPaths = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            foreach (var assemblyPart in parts.OfType<AssemblyPart>())
            {
                var dependencyContext = DependencyContext.Load(assemblyPart.Assembly);
                if (dependencyContext != null)
                {
                    foreach (var library in dependencyContext.CompileLibraries)
                    {
                        if (string.Equals("reference", library.Type, StringComparison.OrdinalIgnoreCase))
                        {
                            foreach (var libraryAssembly in library.Assemblies)
                            {
                                libraryPaths.Add(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, libraryAssembly));
                            }
                        }
                        else
                        {
                            foreach (var path in library.ResolveReferencePaths())
                            {
                                libraryPaths.Add(path);
                            }
                        }
                    }
                }
                else
                {
                    libraryPaths.Add(assemblyPart.Assembly.Location);
                }
            }

            foreach (var path in libraryPaths)
            {
                feature.MetadataReferences.Add(CreateMetadataReference(path));
            }
        }

        private static MetadataReference CreateMetadataReference(string path)
        {
            using (var stream = File.OpenRead(path))
            {
                var moduleMetadata = ModuleMetadata.CreateFromStream(stream, PEStreamOptions.PrefetchMetadata);
                var assemblyMetadata = AssemblyMetadata.Create(moduleMetadata);

                return assemblyMetadata.GetReference(filePath: path);
            }
        }
    }
}

And also replace in your Startup "services.AddMvc()" with the following code:

services.AddMvc() // Следующий патч нужен для компенсации бага компиляции представлений при подключении сборок .NetStandart2.0
    .ConfigureApplicationPartManager(manager =>
    {
        manager.FeatureProviders.Remove(manager.FeatureProviders.First(f => f is MetadataReferenceFeatureProvider));
        manager.FeatureProviders.Add(new ReferencesMetadataReferenceFeatureProvider());
    });

If your app is compiling Razor code in runtime and you are in .netcore2+ it seems you need to add this to your project:

<MvcRazorExcludeRefAssembliesFromPublish>false</MvcRazorExcludeRefAssembliesFromPublish>

This copies the refs folder on publish - it is large - but it seems to be needed

For resolve this problem you should inject IServiceProvider in Startup constructor like this:

 public Startup(IConfiguration configuration, IHostingEnvironment env, IServiceProvider serviceProvider)
    {
        Configuration = configuration;

        var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);

        var mvcBuilder = serviceProvider.GetService<IMvcBuilder>();
        new MvcConfiguration().ConfigureMvc(mvcBuilder);

        Configuration = builder.Build();

    }