web api vs 2017 build failing

Hi,

I have a web api project that won't build when I add a .net framework (4.71) class library project to the solution.  If I remove the class library, the build succeeds.  Error below:

[CoreCompile] Csc
[12:03:15][Csc] C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\15.0\bin\Roslyn\csc.exe /noconfig /nowarn:1701,1702 /nostdlib+ /errorreport:prompt /warn:4 /define:DEBUG;TRACE /highentropyva+ /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\Microsoft.CSharp.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\mscorlib.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\System.Core.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\System.Data.DataSetExtensions.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\System.Data.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\System.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\System.Net.Http.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\System.Xml.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.1\System.Xml.Linq.dll" /debug+ /debug:full /filealign:512 /optimize- /out:obj\Debug\SomeClassLib.dll /subsystemversion:6.00 /target:library /utf8output /deterministic+ Class1.cs Properties\AssemblyInfo.cs "C:\TeamCity\buildAgent2\temp\buildTmp\.NETFramework,Version=v4.7.1.AssemblyAttributes.cs"
[12:03:15][Csc] Using shared compilation with compiler from directory: C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\15.0\bin\Roslyn
[12:03:15][Csc] CSC error CS0041: Unexpected error writing debug information -- 'Unable to load DLL 'Microsoft.DiaSymReader.Native.amd64.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)'