'IServiceCollection' does not contain a definition for 'AddSession'

问题

I am getting an error while adding 'AddSession' in ASP.Net Core 1.1 using VS2017.

'IServiceCollection' does not contain a definition for 'AddSession' and no extension method 'AddSession' accepting a first argument of type 'IServiceCollection' could be found (are you missing a using directive or an assembly reference?)

.csproj

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

<PropertyGroup>
<TargetFramework>netcoreapp1.1</TargetFramework>
</PropertyGroup>

<PropertyGroup>
<PackageTargetFallback>$(PackageTargetFallback);portable-net45+win8+wp8+wpa81;</PackageTargetFallback>
</PropertyGroup>
 <ItemGroup>
  <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.0.0" />
  <PackageReference Include="Microsoft.AspNetCore" Version="1.1.1" />
<PackageReference Include="Microsoft.AspNetCore.Mvc" Version="1.1.2" />
<PackageReference Include="Microsoft.AspNetCore.Session" Version="1.1.2" />
<PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="1.1.1" />
<PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="1.1.1" />
<PackageReference Include="Microsoft.VisualStudio.Web.BrowserLink" Version="1.1.0" />
 </ItemGroup>
 <ItemGroup>
 <DotNetCliToolReference 
 Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="1.0.0" />
</ItemGroup>

 </Project>

Error :

回答1:

You need to include following Nuget package

AutoMapper.Extensions.Microsoft.Dependencyinjection

回答2:

I know this is a bit late, but did you try to install the Microsoft.AspNetCore.Session package from nuget?

https://www.nuget.org/packages/Microsoft.AspNetCore.Session/

In Visual Studio: Install-Package Microsoft.AspNetCore.Session -Version 1.1.2(in my case)

It worked for me!

回答3:

The following way I fixed the Issue.

1. Clean and Rebuild the solution.
2. Restart Visual Studio 2017.

Thanks @HenkMollema

回答4:

The versions of the dependencies seem to be out of sync. Use Nuget to update all your packages to be the same version and that should solve the issue. This applies to most if not all Microsoft.* packages.

Also you need the following using statements:

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using System;

回答5:

Make sure you have

<PackageReference Include="Microsoft.AspNetCore.Session" Vesion="1.1.1" />

(or more up-to-date version) within your .csproj file

回答6:

In my case AutoMapper.Extensions.Microsoft.DependencyInjection (v1 was installed). Uninstalled and installed AutoMapper.Extensions.Microsoft.DependencyInjection v5.0.1

回答7:

It looks like you missed something. In Package Manager Console, write:

install-package Microsoft.AspNetCore.Session -version x.x.x

x.x.x depends on your project reference

回答8:

Adding the nuget package for Scrutor fixed it for me

来源：https://stackoverflow.com/questions/44409554/iservicecollection-does-not-contain-a-definition-for-addsession