.NET Core 2.0 Project Builds But Not When Referenced By Another .NET Core 2.0 Project

Question

I'm on Ubuntu and I have two .NET Core 2.0 projects (Project Oranges.csproj and Apples.csproj). Oranges only contains references to NuGet packages, while Apples contains a reference to Oranges.

Running dotnet build -f netcoreapp2.0 Oranges.csproj succeeds! Oranges.dll now exists at /Oranges/bin/Debug/netcoreapp2.0/Oranges.dll.

Running dotnet build -f netcoreapp2.0 Apples.csproj fails with: error CS0009: Metadata file '/Oranges/bin/Debug/netcoreapp2.0/Oranges.dll' could not be opened -- PE image doesn't contain managed metadata

How can I go about referencing Oranges, which builds without issue, in Apples without issue?

Oranges.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
    <TargetFrameworks>netcoreapp2.0;net451;</TargetFrameworks>
    <RootNamespace>Oranges</RootNamespace>
    <SignAssembly>true</SignAssembly>
    <AssemblyOriginatorKeyFile>..\..\GeneratedKey.snk</AssemblyOriginatorKeyFile>
    <DelaySign>false</DelaySign>
  </PropertyGroup>

  <PropertyGroup Condition="'$(TargetFramework)' == 'netcore2.0'">
    <DefineConstants>NETCORE2_0</DefineConstants>
  </PropertyGroup>
  <PropertyGroup Condition="'$(TargetFramework)' == 'net451'">
    <DefineConstants>NET4_5_1</DefineConstants>
  </PropertyGroup>

  <ItemGroup>
    <None Remove="packages.config" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Newtonsoft.Json" Version="10.0.3" />
    <PackageReference Include="System.Collections.Immutable" Version="1.4.0" />
  </ItemGroup>
</Project>

Apples.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
    <TargetFrameworks>netcoreapp2.0;net451;</TargetFrameworks>
    <RootNamespace>Apples</RootNamespace>
    <SignAssembly>true</SignAssembly>
    <DelaySign>false</DelaySign>
    <AssemblyOriginatorKeyFile>..\..\GeneratedKey.snk</AssemblyOriginatorKeyFile>
  </PropertyGroup>

  <ItemGroup>
    <None Remove="packages.config" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="CommandLineParser" Version="2.1.1-beta" />
    <PackageReference Include="Newtonsoft.Json" Version="10.0.3" />
    <PackageReference Include="System.Collections.Immutable" Version="1.4.0" />
    <PackageReference Include="System.Composition" Version="1.1.0" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Oranges\Oranges.csproj" />
  </ItemGroup>
</Project>

can you provide us the csprojs for apple and oranges. Nice project names btw. — Thomas, Sep 07 '17 at 21:12
use CLI to add reference. MSDN doc [here](https://learn.microsoft.com/en-us/dotnet/core/tools/dotnet-add-reference) — Pratik Gaikwad, Sep 07 '17 at 21:41
@PratikGaikwad Thanks for commenting. I have already added a reference to the project. See the code for `Apples.csproj` above. — Bacon, Sep 07 '17 at 21:48
does this build using msbuild on windows (/ mono 5.2 msbuild on linux)? Full assembly signing doesn't yet work on .net core AFAIK — Martin Ullrich, Sep 08 '17 at 03:59
@Jeff The error you are getting because `Oranges.dll` is being used and locked for execution in its own project. And hence it can't be directly accessed in `Apples.dll`. What you need is `copytolocal` similar to .net framework. But in doing net cor we have two options. 1) you can use `dotnet publish` command or 2) or for local testing you can set `true` source from this [SO](https://stackoverflow.com/questions/43837638/how-to-get-net-core-projects-to-copy-nuget-references-to-build-output). Let me know if it works or not. — Pratik Gaikwad, Sep 08 '17 at 12:44

score 2 · Accepted Answer · answered Sep 08 '17 at 18:44

After deleting the bin and obj folders from the project directory and rebuilding, a different error was being displayed.

CSC : error CS7027: Error signing output with public key from file 'GeneratedKey.snk' -- Assembly signing not supported. [.../Oranges/Oranges.csproj]

After some research I stumbled across a solution.

Assembly Signing Not Supported

Adding the line below to the .csproj file for each assembly that required signing resolved the issue.

<PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>

For now it seems like if you need to sign netcore assemblies, it should be done on Windows.

Make sense. Signing was the only "strange" thing in your sample. It is a feature of the past. — Thomas, Sep 09 '17 at 06:39

.NET Core 2.0 Project Builds But Not When Referenced By Another .NET Core 2.0 Project

1 Answers1