How to compile c# csproj into exe in Visual Studio 2015 - error CS0579

You should delete this entire line from AssemblyInfo.cs:

[assembly: System.Runtime.Versioning.TargetFramework(".NETFramework,Version=v4.0,Profile=Cl‌​ient", FrameworkDisplayName=".NET Framework 4 Client Profile")] 

I had today the error CS0579 related to some AssemblyInfo and TargetFrameworkAttribute duplicated values. Using sdk 3.1.301 and targetting netcoreapp3.1 and with some other projects targeting netstandard2.1

Using this:

    <PropertyGroup>
        <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
        <GenerateTargetFrameworkAttribute>false</GenerateTargetFrameworkAttribute>
    </PropertyGroup>

And deleting /bin & /obj fixed my build.