If you aren't sure if you already have the developer pack installed, you can check your Windows Registry: Open regedit.exe .
Ensure your OS is compatible. Note that version 4.5 was a "highly compatible, in-place update" to version 4.0. microsoft .net framework 4.5 developer pack download
Provides tools, compilers, and libraries for building apps. Download and Installation Guide Official Source Microsoft Download Center Supported OS Windows 7 SP1, Windows 8, Windows Server 2008 R2 SP1, 2012 Visual Studio Version Recommended for Visual Studio 2012 and later Step-by-Step Installation If you aren't sure if you already have
If you are developing new applications, it is highly recommended to use Microsoft .NET 8.0 or Microsoft .NET Framework 4.8.1 , which are modern and actively supported. How to Check Your Current Version Provides tools, compilers, and libraries for building apps
For newer Windows versions, you may need to enable the framework via Turn Windows features on or off in the Control Panel. Microsoft .NET Framework - Microsoft Lifecycle
Locate the official Microsoft .NET Framework 4.5 Developer Pack executable.
Informs Visual Studio about the specific APIs available in version 4.5.