Unable to build for Windows after installing Visual Studio 2017

Recently I uninstalled Visual Studio Community 2015 and installed Visual Studio Community 2017. Now I am unable to create a Windows build in Unity. Here is the error I am getting:

Could not start compilationDirectoryNotFoundException: Directory 'C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETCore\v4.5.1' not found.
System.IO.Directory.GetFileSystemEntries (System.String path, System.String searchPattern, FileAttributes mask, FileAttributes attrs) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.IO/Directory.cs:528)
System.IO.Directory.GetFiles (System.String path, System.String searchPattern) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.IO/Directory.cs:308)
UnityEditor.Scripting.Compilers.MicrosoftCSharpCompiler.GetNETWSAAssemblies (WSASDK wsaSDK) (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/MicrosoftCSharpCompiler.cs:108)
UnityEditor.Scripting.Compilers.MicrosoftCSharpCompiler.FillNETCoreCompilerOptions (WSASDK wsaSDK, System.Collections.Generic.List`1 arguments, System.String& argsPrefix) (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/MicrosoftCSharpCompiler.cs:203)
UnityEditor.Scripting.Compilers.MicrosoftCSharpCompiler.StartCompiler () (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/MicrosoftCSharpCompiler.cs:311)
UnityEditor.Scripting.Compilers.ScriptCompilerBase.BeginCompiling () (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/ScriptCompilerBase.cs:47)
UnityEditor.HostView:OnGUI()

It looks like when I uninstalled VS 2015 it removed .NETCore\v4.5.1 (the folder no longer exists on my system). I Unity unable to use .NETCore\v5.0?

Thanks,

Jonathan L Clark

Man, i made that some weeks ago and i had a similar problem…
i just unninstall unity and install it again and every thing works very well.

i think thats is the last option.