: Download the Microsoft.NETFramework.ReferenceAssemblies.net45 package from NuGet . This allows you to build apps targeting 4.5 without the full developer pack installed.
: You can acquire developer packs directly without downloading manual files. Open the Visual Studio Installer on your machine, navigate to your active installation, and search for individual components to check off older .NET Framework targeting packs. ⚠️ Important Support Notice net framework 45 developer pack link