.NET Standard class library could not load file or assembly Microsoft.Data.Sqlite

Question

I am trying to create a .NET Standard class library which accesses a SQLite database. After much research, I thought that Microsoft.Data.Sqlite would work best.

But I get the following exception when calling a class library method that needs the package:

Could not load file or assembly 'Microsoft.Data.Sqlite, Version=2.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' or one of its dependencies. The system cannot find the file specified.

I have isolated the problem in a very simple console application using .NET Framework 4.6.2 that calls the method in a .NET Standard 2.0 class library. I added Microsoft.Data.Sqlite 2.1.0 to the class library using the NuGet Package Manager. I am using Visual Studio Community 2017 (version 15.8.3) on Windows 10.

I had no problems when creating a .NET Core 2.1 console application that directly used Microsoft.Data.Sqlite (that is, there was no separate .NET Standard class library).

The closest question on Stack Overflow is the following, but it doesn't address my problem:

Exception while loading assemblies: Could not load assembly 'Microsoft.Data.Sqlite'

The context for this question is that I am trying to create a desktop application for both Windows and Mac. My hope was to create a .NET Standard class library to handle data access, using SQLite as the actual database. I am open to other suggestions.

I tried adding Microsoft.Data.Sqlite.Core, as well as replacing Microsoft.Data.Sqlite with Microsoft.Data.Sqlite.Core, and I get the same exception. — Joe Lin, Sep 09 '18 at 06:43
I guess you manage packages with the packages.config file. You should use *PackageReference in project file* as shown here https://learn.microsoft.com/en-us/nuget/quickstart/install-and-use-a-package-in-visual-studio#add-the-newtonsoftjson-nuget-package — Sir Rufo, Sep 09 '18 at 06:52

Sir Rufo · Answer 1 · 2018-09-09T11:00:41.437

This seems to be a bug in Visual Studio and in Microsoft.Data.Sqlite package

I have a class library

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Data.Sqlite" Version="2.1.0" />
  </ItemGroup>

</Project>

and 3 project files referencing this class library

first:

<?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>{8DA91D88-9D79-4F06-BEA4-00C408542D4F}</ProjectGuid>
    <OutputType>Exe</OutputType>
    <RootNamespace>ConsoleApp3</RootNamespace>
    <AssemblyName>ConsoleApp3</AssemblyName>
    <TargetFrameworkVersion>v4.6.2</TargetFrameworkVersion>
    <FileAlignment>512</FileAlignment>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <Deterministic>true</Deterministic>
  </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="System" />
    <Reference Include="System.Core" />
    <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" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\ClassLibrary1\ClassLibrary1.csproj">
      <Project>{eb6c148b-91a1-4f10-8703-2b93af5c4de6}</Project>
      <Name>ClassLibrary1</Name>
    </ProjectReference>
  </ItemGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>

second:

<?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>{292E456C-AD14-452A-8D12-409157D79673}</ProjectGuid>
    <OutputType>Exe</OutputType>
    <RootNamespace>ConsoleApp2</RootNamespace>
    <AssemblyName>ConsoleApp2</AssemblyName>
    <TargetFrameworkVersion>v4.6.2</TargetFrameworkVersion>
    <FileAlignment>512</FileAlignment>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <Deterministic>true</Deterministic>
  </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="System" />
    <Reference Include="System.Core" />
    <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" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\ClassLibrary1\ClassLibrary1.csproj">
      <Project>{eb6c148b-91a1-4f10-8703-2b93af5c4de6}</Project>
      <Name>ClassLibrary1</Name>
    </ProjectReference>
  </ItemGroup>
  <ItemGroup>
    <PackageReference Include="Newtonsoft.Json">
      <Version>11.0.2</Version>
    </PackageReference>
  </ItemGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>

third:

<?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>{FBE757BF-025E-4167-90D0-EAD60E50C7EB}</ProjectGuid>
    <OutputType>Exe</OutputType>
    <RootNamespace>ConsoleApp1</RootNamespace>
    <AssemblyName>ConsoleApp1</AssemblyName>
    <TargetFrameworkVersion>v4.6.2</TargetFrameworkVersion>
    <FileAlignment>512</FileAlignment>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <Deterministic>true</Deterministic>
  </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="System" />
    <Reference Include="System.Core" />
    <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" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\ClassLibrary1\ClassLibrary1.csproj">
      <Project>{eb6c148b-91a1-4f10-8703-2b93af5c4de6}</Project>
      <Name>ClassLibrary1</Name>
    </ProjectReference>
  </ItemGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Data.Sqlite">
      <Version>2.1.0</Version>
    </PackageReference>
    <PackageReference Include="Newtonsoft.Json">
      <Version>11.0.2</Version>
    </PackageReference>
  </ItemGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>

The first project did not find the Microsoft.Data.Sqlite.dll as you wrote.
The second project will find the Microsoft.Data.Sqlite.dll but is missing some the e_sqlite3.dll files
The third project will run fine.

The difference between these three projects:

Project1 references ClassLibrary1
Project2 references ClassLibrary1 and NuGet NewtonSoft.Json
Project3 references ClassLibrary1 and NuGet NewtonSoft.Json, Microsoft.Dara.Sqlite

(NewtonSoft.Json - you can use any NuGet package as long as you have referenced a NuGet package and use PackageReference).

VS Bug

If you did not add a reference via PackageReference to any NuGet package the project will not include any NuGet package references from included projects

Microsoft.Data.Sqlite

The needed files x64/x86 e_sqlite3.dll files will only be copied when the package is referenced directly by the application project.

score 0 · Answer 2 · answered Mar 02 '21 at 00:58

I just got it to work by Explicitly adding

<PackageReference Include="Microsoft.Data.Sqlite" Version="$(MicrosoftDataSqliteVersion)" />

To the underlying projects that have references to your original project. Microsoft.Data.Sqlite is getting referenced properly now

.NET Standard class library could not load file or assembly Microsoft.Data.Sqlite

2 Answers2

VS Bug

Microsoft.Data.Sqlite