System.IO.FileLoadException: Could not load file or assembly 'netstandard, Version=2.1.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The located assembly's manifest definition does not match the assembly reference.

[siada]

After upgrading a project from .net core 2.2 to .net core 3.0 I can no longer create ef migrations without encountering the above error

Steps to reproduce

csproj:

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

  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Hangfire.Core" Version="1.7.7" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="3.0.0">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
  </ItemGroup>

  <ItemGroup>
    <FrameworkReference Include="Microsoft.AspNetCore.App" />
  </ItemGroup>

</Project>

cli:
dotnet ef migrations add "Added ContentType to Attachment"

Further technical details

EF Core version: 3.0.0
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET Core 3.0
Operating system: Windows 10
IDE: Visual Studio 2019 16.3

Exception:

System.IO.FileLoadException: Could not load file or assembly 'netstandard, Version=2.1.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
File name: 'netstandard, Version=2.1.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'
   at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type, ObjectHandleOnStack keepAlive)
   at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase)
   at Microsoft.EntityFrameworkCore.Tools.ReflectionOperationExecutor..ctor(String assembly, String startupAssembly, String projectDir, String dataDirectory, String rootNamespace, String language)
   at Microsoft.EntityFrameworkCore.Tools.Commands.ProjectCommandBase.CreateExecutor()
   at Microsoft.EntityFrameworkCore.Tools.Commands.MigrationsAddCommand.Execute()
   at Microsoft.DotNet.Cli.CommandLine.CommandLineApplication.Execute(String[] args)
   at Microsoft.EntityFrameworkCore.Tools.Program.Main(String[] args)


Could not load file or assembly 'netstandard, Version=2.1.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) ```

[siada]

Turns out I had a global.json lurking around with sdk version of 2.2.4 in it... Issue fixed

[siavashkouhgard]

hi
you should change target framework