We have a .NET application compiled with .NET Framework 4.5 as a target. The riddle is: why does this application work on Windows 7 with only .NET Framework 4.0 installed but not on Windows Server 2003 with the same .NET Framework 4.0 installed? The answer it twofold. The first part is easy: 1. Why does the application compiled with .NET Framework 4.5 as a target even works with .NET Framework 4.0? It is because the CLR is still the same. It is 4.0. Have a look with ildasm at a simple exe or dll targeted for .NET Fraemwork 4.5 and you will see: So the app will work but, as…