当项目升级到 .Net Framework 4.7.2 时，从面向项目的 .Net Framework 4.6 引用的 DLL 不再出现在 bin 中

Question

I have two projects, [Service] and [Web]. Both were originally built targeting .Net Framework 4.6. [Web] references [Service], and uses some of the DLLs (specially, System.Runtime.InteropServices.RuntimeInformation.dll and System.Net.Http.dll ) that [Service] has installed via NuGet packages.

[Web] needs to upgrade to target .Net Framework 4.7.2. This has been done, however, those two DLLs from [Service] no longer appear in the bin/ directory of [Web].

I am using Visual Studio 2017 Enterprise.

• I have confirmed that if I downgrade [Web] to .Net Framework 4.6, the DLLs reappear. However, [Web] needs to be on 4.7.2 for other DLLs, and [Service] needs to remain on 4.6.
• System.Runtime.InteropServices.RuntimeInformation.dll comes from Microsoft.AspNetCore.Mvc
• System.Net.Http comes from its own Nuget package

EDIT:

I have since found this buried deep into the detailed log of the build:

Unified Dependency "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a".
29>        Using this version instead of original version "4.0.1.0" in "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.hosting\1.1.2\lib\net451\Microsoft.AspNetCore.Hosting.dll" because AutoUnify is 'true'.
29>        Using this version instead of original version "4.0.1.0" in "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.server.kestrel\1.1.2\lib\net451\Microsoft.AspNetCore.Server.Kestrel.dll" because AutoUnify is 'true'.
29>        Using this version instead of original version "4.0.1.0" in "C:\Users\baker\.nuget\packages\microsoft.extensions.logging.console\1.1.2\lib\net451\Microsoft.Extensions.Logging.Console.dll" because AutoUnify is 'true'.
29>        Resolved file path is "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.2\Facades\System.Runtime.InteropServices.RuntimeInformation.dll".
29>        Reference found at search path location "{TargetFrameworkDirectory}".
29>            For SearchPath "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.hosting\1.1.2\lib\net451".
29>            Considered "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.hosting\1.1.2\lib\net451\System.Runtime.InteropServices.RuntimeInformation.winmd", but it didn't exist.
29>            Considered "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.hosting\1.1.2\lib\net451\System.Runtime.InteropServices.RuntimeInformation.dll", but it didn't exist.
29>            Considered "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.hosting\1.1.2\lib\net451\System.Runtime.InteropServices.RuntimeInformation.exe", but it didn't exist.
29>            For SearchPath "{CandidateAssemblyFiles}".
29>            Considered "net472Dlls\System.Net.Http.dll",
29>             but its name "System.Net.Http"
29>             didn't match the expected name "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a".
29>            Considered "net472Dlls\System.Runtime.InteropServices.RuntimeInformation.dll",
29>             but its name "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
29>             didn't match the expected name "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a".
29>            For SearchPath "{TargetFrameworkDirectory}".
29>            Considered "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.2\System.Runtime.InteropServices.RuntimeInformation.winmd", but it didn't exist.
29>            Considered "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.2\System.Runtime.InteropServices.RuntimeInformation.dll", but it didn't exist.
29>            Considered "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.2\System.Runtime.InteropServices.RuntimeInformation.exe", but it didn't exist.
29>            Considered "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.2\Facades\System.Runtime.InteropServices.RuntimeInformation.winmd", but it didn't exist.
29>        Required by "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.hosting\1.1.2\lib\net451\Microsoft.AspNetCore.Hosting.dll".
29>        Required by "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.server.kestrel\1.1.2\lib\net451\Microsoft.AspNetCore.Server.Kestrel.dll".
29>        Required by "C:\Users\baker\.nuget\packages\microsoft.aspnetcore.server.kestrel.https\1.1.2\lib\net451\Microsoft.AspNetCore.Server.Kestrel.Https.dll".
29>        Required by "C:\Users\baker\.nuget\packages\microsoft.extensions.logging.console\1.1.2\lib\net451\Microsoft.Extensions.Logging.Console.dll".
29>        This reference is not "CopyLocal" because it conflicted with another reference with the same name and lost the conflict.
29>        The ImageRuntimeVersion for this reference is "v4.0.30319".

Answer 1

Sounds like this issue .

From the link:

The workaround is to add an extra package reference to your project file and exclude all of its assets in order to make sure that the package implementation is never preferred. This ensures that the platform version wins and is not removed by the NuGet targets. Here is an example of how to do this for the System.Net.Http.dll case:

<ItemGroup>
    <PackageReference Include="System.Net.Http" Version="4.3.3">
         <ExcludeAssets>All</ExcludeAssets> 
    </PackageReference>
</ItemGroup>