Project 'PalringoApi.Core' load failed

I can't load my project. I got 3 errors:

12:39 PM Project 'PalringoApi.Core' load failed: The imported project "F:\Program Files (x86)\Test\MSBuild\15.0\Bin\Roslyn\Microsoft.CSharp.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk. F:\Program Files (x86)\Test\MSBuild\15.0\Bin\Microsoft.CSharp.CurrentVersion.targets at (322:5)

12:39 PM Project 'PalringoApi.Plugins' load failed: The imported project "F:\Program Files (x86)\Test\MSBuild\15.0\Bin\Roslyn\Microsoft.CSharp.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk. F:\Program Files (x86)\Test\MSBuild\15.0\Bin\Microsoft.CSharp.CurrentVersion.targets at (322:5)

12:39 PM Project 'PalringoApi.Test' load failed: The imported project "F:\Program Files (x86)\Test\MSBuild\15.0\Bin\Roslyn\Microsoft.CSharp.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk. F:\Program Files (x86)\Test\MSBuild\15.0\Bin\Microsoft.CSharp.CurrentVersion.targets at (322:5)