Using SDK v. 3.7.0 in netstandard 2.0 project results in Could not load file or assembly exception

[zengouu]

Describe the bug
After installing Microsoft.Azure.Cosmos v. 3.7.0 to a netstandard2.0 class library that is called from .NET Framework 4.7.2 Console app throws an error of:

Could not load file or assembly 'Microsoft.Azure.Cosmos.Client, Version=3.7.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

To Reproduce

• Start up local cosmos db emulator
• Create a solution and add a new .netstandard 2.0 class library project
• Add package Microsoft.Azure.Cosmos v. 3.7.0 via NuGet
• Add a new .NET Framework 4.7.2 Console App Project
• Call method in class library that creates a new cosmos db database

Code:

using System.Threading.Tasks;
using TestLibrary;

namespace TestConsole
{
	class Program
	{
		static async Task Main(string[] args)
		{
			var lib = new Class1();
			await lib.TestCosmos(); // App crashes when this is called.
		}
	}
}

using System;
using System.Threading.Tasks;
using Microsoft.Azure.Cosmos;

namespace TestLibrary
{
	public class Class1
	{
		public async Task TestCosmos()
		{
			// This line is never reached

			var data = new Dto
			{
				Id = Guid.NewGuid(),
				Name = string.Empty
			};

			using ( CosmosClient client = new CosmosClient( "https://localhost:8081", "C2y6yDjf5/....." ) )
			{
				var dbResponse = await client.CreateDatabaseIfNotExistsAsync( "QueryDb" );
				var container = await dbResponse.Database.CreateContainerIfNotExistsAsync( "container", "/cont" );

				ItemResponse<Dto> response = await container.Container.CreateItemAsync( data, null );
			}
		}
	}

	public class Dto
	{
		public Guid Id { get; set; }
		public string Name { get; set; }
	}
}

Expected behavior
To my understanding this should work without a problem. Microsoft.Azure.Cosmos nuget changelog says the following:
Targets .NET Standard 2.0, which supports .NET framework 4.6.1+ and .NET Core 2.0+

Actual behavior
Calling class library method results in a following error:
Could not load file or assembly 'Microsoft.Azure.Cosmos.Client, Version=3.7.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

Environment summary
SDK Version: 3.7.0
OS Version: Windows 10 Pro, Version 10.0.18363 Build 18363

Additional context
I also tried with following versions of Microsoft.Azure.Cosmos:
3.6.0
3.4.0

[ealsur]

You don't need to add the netstandard package.

What Visual Studio version are you using?

[ealsur]

If I create a new NET 4.7.2 console application and just add the Microsoft.Azure.Cosmos Nuget, this is what the CSPROJ looks like:

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <ProjectGuid>{2D7E3FB8-79D9-41CD-B773-924C9FB0BD2E}</ProjectGuid>
    <OutputType>Exe</OutputType>
    <RootNamespace>ConsoleApp1</RootNamespace>
    <AssemblyName>ConsoleApp1</AssemblyName>
    <TargetFrameworkVersion>v4.7.2</TargetFrameworkVersion>
    <FileAlignment>512</FileAlignment>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <Deterministic>true</Deterministic>
    <NuGetPackageImportStamp>
    </NuGetPackageImportStamp>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <PlatformTarget>AnyCPU</PlatformTarget>
    <DebugSymbols>true</DebugSymbols>
    <DebugType>full</DebugType>
    <Optimize>false</Optimize>
    <OutputPath>bin\Debug\</OutputPath>
    <DefineConstants>DEBUG;TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    <PlatformTarget>AnyCPU</PlatformTarget>
    <DebugType>pdbonly</DebugType>
    <Optimize>true</Optimize>
    <OutputPath>bin\Release\</OutputPath>
    <DefineConstants>TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <ItemGroup>
    <Reference Include="Microsoft.Azure.Cosmos.Client, Version=3.7.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
      <HintPath>packages\Microsoft.Azure.Cosmos.3.7.0\lib\netstandard2.0\Microsoft.Azure.Cosmos.Client.dll</HintPath>
    </Reference>
    <Reference Include="Microsoft.Azure.Cosmos.Core, Version=2.4.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
      <HintPath>packages\Microsoft.Azure.Cosmos.3.7.0\lib\netstandard2.0\Microsoft.Azure.Cosmos.Core.dll</HintPath>
    </Reference>
    <Reference Include="Microsoft.Azure.Cosmos.Direct, Version=3.7.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
      <HintPath>packages\Microsoft.Azure.Cosmos.3.7.0\lib\netstandard2.0\Microsoft.Azure.Cosmos.Direct.dll</HintPath>
    </Reference>
    <Reference Include="Microsoft.Azure.Cosmos.Serialization.HybridRow, Version=2.4.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
      <HintPath>packages\Microsoft.Azure.Cosmos.3.7.0\lib\netstandard2.0\Microsoft.Azure.Cosmos.Serialization.HybridRow.dll</HintPath>
    </Reference>
    <Reference Include="Newtonsoft.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
      <HintPath>packages\Newtonsoft.Json.10.0.2\lib\net45\Newtonsoft.Json.dll</HintPath>
    </Reference>
    <Reference Include="System" />
    <Reference Include="System.Buffers, Version=4.0.2.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>packages\System.Buffers.4.4.0\lib\netstandard2.0\System.Buffers.dll</HintPath>
    </Reference>
    <Reference Include="System.Configuration" />
    <Reference Include="System.Configuration.ConfigurationManager, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>packages\System.Configuration.ConfigurationManager.4.5.0\lib\net461\System.Configuration.ConfigurationManager.dll</HintPath>
    </Reference>
    <Reference Include="System.Core" />
    <Reference Include="System.Data.OracleClient" />
    <Reference Include="System.Drawing" />
    <Reference Include="System.IdentityModel" />
    <Reference Include="System.Memory, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>packages\System.Memory.4.5.1\lib\netstandard2.0\System.Memory.dll</HintPath>
    </Reference>
    <Reference Include="System.Net" />
    <Reference Include="System.Numerics" />
    <Reference Include="System.Numerics.Vectors, Version=4.1.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
      <HintPath>packages\System.Numerics.Vectors.4.4.0\lib\net46\System.Numerics.Vectors.dll</HintPath>
    </Reference>
    <Reference Include="System.Runtime.CompilerServices.Unsafe, Version=4.0.4.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
      <HintPath>packages\System.Runtime.CompilerServices.Unsafe.4.5.1\lib\netstandard2.0\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
    </Reference>
    <Reference Include="System.Runtime.Serialization" />
    <Reference Include="System.Security.AccessControl, Version=4.1.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
      <HintPath>packages\System.Security.AccessControl.4.5.0\lib\net461\System.Security.AccessControl.dll</HintPath>
    </Reference>
    <Reference Include="System.Security.Permissions, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>packages\System.Security.Permissions.4.5.0\lib\net461\System.Security.Permissions.dll</HintPath>
    </Reference>
    <Reference Include="System.Security.Principal.Windows, Version=4.1.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
      <HintPath>packages\System.Security.Principal.Windows.4.5.0\lib\net461\System.Security.Principal.Windows.dll</HintPath>
    </Reference>
    <Reference Include="System.ServiceModel" />
    <Reference Include="System.ServiceModel.Primitives, Version=4.5.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
      <HintPath>packages\System.ServiceModel.Primitives.4.5.0\lib\net461\System.ServiceModel.Primitives.dll</HintPath>
    </Reference>
    <Reference Include="System.ServiceProcess" />
    <Reference Include="System.Threading.Tasks.Extensions, Version=4.2.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>packages\System.Threading.Tasks.Extensions.4.5.1\lib\netstandard2.0\System.Threading.Tasks.Extensions.dll</HintPath>
    </Reference>
    <Reference Include="System.Transactions" />
    <Reference Include="System.ValueTuple, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
      <HintPath>packages\System.ValueTuple.4.5.0\lib\net47\System.ValueTuple.dll</HintPath>
    </Reference>
    <Reference Include="System.Xml.Linq" />
    <Reference Include="System.Data.DataSetExtensions" />
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="System.Data" />
    <Reference Include="System.Net.Http" />
    <Reference Include="System.Xml" />
  </ItemGroup>
  <ItemGroup>
    <Compile Include="Program.cs" />
    <Compile Include="Properties\AssemblyInfo.cs" />
  </ItemGroup>
  <ItemGroup>
    <None Include="App.config" />
    <None Include="packages.config" />
  </ItemGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
  <Import Project="packages\Microsoft.Azure.Cosmos.3.7.0\build\netstandard2.0\Microsoft.Azure.Cosmos.targets" Condition="Exists('packages\Microsoft.Azure.Cosmos.3.7.0\build\netstandard2.0\Microsoft.Azure.Cosmos.targets')" />
  <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
    <PropertyGroup>
      <ErrorText>This project references NuGet package(s) that are missing on this computer. Use NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
    </PropertyGroup>
    <Error Condition="!Exists('packages\Microsoft.Azure.Cosmos.3.7.0\build\netstandard2.0\Microsoft.Azure.Cosmos.targets')" Text="$([System.String]::Format('$(ErrorText)', 'packages\Microsoft.Azure.Cosmos.3.7.0\build\netstandard2.0\Microsoft.Azure.Cosmos.targets'))" />
  </Target>
</Project>

[zengouu]

Thanks for the answer @ealsur, installing Microsoft.Azure.Cosmos also to the console application indeed fixes the problem. The code which uses Cosmos Db can still be located in the class library.

I'd appreciate if someone could share some light on why this approach works but when the nuget is only installed on the class library it does not :) Just asking to get a better understanding of this situation.

In any case this solves the problem I am facing so I'll close the issue.

[ealsur]

TLDR: Add <RestoreProjectStyle>PackageReference</RestoreProjectStyle> to your NET Framework CSPROJ within a <PropertyGroup> node.

This is not an issue of the SDK, it is rather an issue of NET Framework with NET Standard class libraries and VS.

See the Workarounds section at: dotnet/standard#481

This is reported in a bunch of other places:

• Referencing a .net standard class library project in .net Framework web app and System.IO.FileNotFoundException throws dotnet/standard#410
• https://www.hanselman.com/blog/ReferencingNETStandardAssembliesFromBothNETCoreAndNETFramework.aspx