Azure function V3 could not load file or assembly Microsoft.Extensions.DependencyInjection.Abstractions, Version=5.0.0.0 with EF core 5.0-rc1

问题

Case

We are creating azure function v3 with .netcore 3.1. Using EF core 5.0-rc1 and Depdency Injection

1) DependecyInjection

[assembly: FunctionsStartup(typeof(xxxxx.Startup))]
namespace xxxxx
{
    public class Startup : FunctionsStartup
    {
        public override void Configure(IFunctionsHostBuilder builder)
        {
            var services = builder.Services;
            var configBuilder = new ConfigurationBuilder()
                .SetBasePath(Environment.CurrentDirectory)
                .AddJsonFile("local.settings.json", true, reloadOnChange: true)
                .AddEnvironmentVariables() ;
            ConfigureServices(services);
            ConfigureAppSettings(services, configBuilder.Build());
            ConfigureLogging(services, configBuilder.Build());
        }
    }
}

2) EF core 5.0 rc-1

https://devblogs.microsoft.com/dotnet/announcing-entity-framework-core-efcore-5-0-rc1/

Error

Could not load file or assembly 'Microsoft.Extensions.DependencyInjection.Abstractions, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.

Packages

Following are the packages referenced

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AzureFunctionsVersion>v3</AzureFunctionsVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Azure.Functions.Extensions" Version="1.1.0" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.ServiceBus" Version="4.1.0" />
    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="5.0.0-rc.1.20451.14" />
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="3.0.7" />
    <PackageReference Include="Serilog.Extensions.Logging" Version="3.0.1" />
    <PackageReference Include="Serilog.Sinks.Console" Version="3.1.1" />
  </ItemGroup>
  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <CopyToPublishDirectory>Never</CopyToPublishDirectory>
    </None>
  </ItemGroup>
</Project>

Troubleshooting

commenting the following line in startup.cs (Dependency injection) solves the problem

[assembly: FunctionsStartup(typeof(xxxxx.Startup))]

回答1:

The Microsoft.Azure.Functions.Extensions depends on .net standard 2.0.

While the Entity Framework Core 5.0 RC1 will not run on .Net standard 2.0 platforms, it requires .net standard 2.1. So it could not find the Microsoft.Azure.Functions.Extensions.

For more details, you could refer to this article.

回答2:

If you are using .NET core 3.1 or below that. Downgrade the NuGet packages of Microsoft.Extensions.DependencyInjection and Microsoft.Extensions.DependencyInjection.Abstractions to 3.1.11.

回答3:

It's not supported in Azure Function v3, yet. https://github.com/Azure/azure-functions-vs-build-sdk/issues/472

But, if you want to test it locally, I was able to run updating the DLL's in the Azure Function Core Tools directory: C:\Program Files\Microsoft\Azure Functions Core Tools

I needed to replace/update these Dll's to use EF5 with my functions: Dll's list

Microsoft.Extensions.DependencyInjection.Abstractions.dll
Microsoft.Extensions.Logging.Abstractions.dll
Microsoft.Extensions.Options.dll
Microsoft.Extensions.Primitives.dll

回答4:

I have a .Net Standard 2.1 lib project with a service that is injected into my function app. In my solution the lib referenced:

Microsoft.Extensions.Options v5.0.0

After I changed the package version to 3.1.11, my function app ran successfully. In other words, if any project referenced by your function app has a reference to a .Net 5.0 package, it looks like you will get this exception if you are using DI.

Current versions in my function app:
Function app: .Net Core 3.1
Azure Functions Version: 3
Other libs: .Net Standard 2.1

I started with .Net 5.0 for the function app but apparently that is not supported for now:
.NET 5 support on Azure Functions

Hopefully this answer will be obsolete before too long but as of Jan 24, 2021 don't use .Net 5.0 projects or package references in your Azure function app solution/projects.

来源：https://stackoverflow.com/questions/63972495/azure-function-v3-could-not-load-file-or-assembly-microsoft-extensions-dependenc

标签

dependency-injection

entity-framework-core

azure-functions