msbuild: Cannot find reference assemblies for .NET 3.5 or lower using core msbuild

I got this working by adding the following to the .csproj file:

<PropertyGroup>
  <FrameworkPathOverride Condition="'$(TargetFramework)' == 'net35'">$(MSBuildProgramFiles32)\Reference Assemblies\Microsoft\Framework\.NETFramework\v3.5\Profile\Client</FrameworkPathOverride>
</PropertyGroup>

Unfortunately, the “normal” path C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v3.5 doesn’t work in this case because it doesn’t have a copy of mscorlib.dll.

Update

This can now be addressed using the Microsoft.NETFramework.ReferenceAssemblies NuGet package. Click through to the “Project Website” for documentation.

Issues a pain when you’re trying to generate a multi-target nuget package; prior to the great cheese moving of 2016 I had no issues building a package that targeted 2/3.5/4/4.5/etc Is this likely to be sorted in the next few days when VS17s released? Seems ambitious…

Admittedly I’m presuming this is msbuild related as it came with RC4 / VS2017 changes and the issue in the error being thrown is the same as the op (albeit for every version specified).

<PropertyGroup>
      ...  <TargetFrameworks>net20;net35;net40;net45;net451;net452;net462;netstandard1.3;netstandard1.6;netstandard1.6.1;netcoreapp1.1</TargetFrameworks>
    ...

etc https://github.com/BcryptNet/bcrypt.net/blob/master/src/BCrypt.Net/BCrypt.Net.csproj

Hell, it might be that after all these changes and dotnet versions I need to set fire to my PC and start afresh to get things to build 🔥

Yeah, that doesn’t work for me, as there is no 3.5 version of System.Web available anywhere in that folder structure. 😞

What’s the work-around for people who need to build such projects on VS 2017? I just ran into this today, and the only thing I could figure out was to compile on a separate machine with only VS 2015 installed.

@JoshClose you can directly call

msbuild /t:Pack /p:Configuration=Release

For version suffixes, add /p:VersionSuffix=beta-123 (however, note https://github.com/NuGet/Home/issues/4337)

I see. I think that’s the answer to my question… 😄

(don’t use dotnet build -f net35, use msbuild /p:TargetFramework=net35)

Should we we expect support from the CLI to .NET 3.5 eventually or is this just not planned?

The @NightOwl888 solution stopped working again.

C:\Program Files\dotnet\sdk\2.0.2\Sdks\Microsoft.NET.Sdk\build\Microsoft.PackageDependencyResolution.targets(165,5): error : Assets file '...\obj\project.assets.json' doesn't have a target for '.NETFramework,Version=v3.5,Profile=Client'. Ensure that restore has run and that you have included 'net35-client' in the TargetFrameworks for your project.