title: F# core .NET framework on Linux build how-to
body: <p>I'm trying to build a F# project (console) on Ubuntu 17.10 (Mono 4.6.2) however I run into F# core .NET issues. For reference, I'm using Visual Studio Code 1.21.2 and ionide extensions (new project and FAKE build). Below is the output.</p>
  <p>I've tried adding an explicit reference to different versions of Fsharp.core e.g. 4.2, 4.3.4 with no luck.</p>
  <p>Where should I be looking at to sort this out?</p>
  <pre class="lang-none prettyprint-override"><code>Finished Target: InstallDotNetCLI
  Starting Target: Restore (==&gt; InstallDotNetCLI)
  /home/lear/.local/share/dotnetcore/dotnet restore
    Restoring packages for /home/lear/src/fsTest/fsTest/fsTest.fsproj...
  /home/lear/src/fsTest/fsTest/fsTest.fsproj : error NU1100: Unable to resolve 'FSharp.Core (&gt;= 4.3.4)' for '.NETFramework,Version=v4.6.1'.
    Restore failed in 99.61 ms for /home/lear/src/fsTest/fsTest/fsTest.fsproj.
  Running build failed.
  
  
   &lt;ItemGroup&gt;
      &lt;PackageReference Update=&quot;FSharp.Core&quot; Version=&quot;4.3.4&quot; /&gt;
    &lt;/ItemGroup&gt;
  </code></pre>
  <p>The project file looks like this:</p>
  <pre><code>&lt;Project Sdk=&quot;Microsoft.NET.Sdk&quot;&gt;
    &lt;PropertyGroup&gt;
      &lt;OutputType&gt;Exe&lt;/OutputType&gt;
      &lt;TargetFramework&gt;net461&lt;/TargetFramework&gt;
    &lt;/PropertyGroup&gt;
    &lt;ItemGroup&gt;
      &lt;ProjectReference Include=&quot;fsTest.fsproj&quot;&gt;
        &lt;Name&gt;fsTest.fsproj&lt;/Name&gt;
      &lt;/ProjectReference&gt;
    &lt;/ItemGroup&gt;
    &lt;ItemGroup&gt;
      &lt;Compile Include=&quot;fsTest.fs&quot; /&gt;
      &lt;None Include=&quot;App.config&quot; /&gt;
    &lt;/ItemGroup&gt;
    &lt;Import Project=&quot;..\.paket\Paket.Restore.targets&quot; /&gt;
  &lt;/Project&gt;
  </code></pre>
  <p>I used this instructions as reference for my setup:
  <em><a href="https://medium.com/@edgarsanchezg/four-easy-steps-for-installing-f-in-ubuntu-linux-88122323f12b" rel="nofollow noreferrer">Four easy steps for installing F# on Ubuntu Linux</a></em> (2017-07-03)</p>