If you are setting up a modern development environment, Microsoft recommends installing the .NET Framework 4.8 Developer Pack , as it is the last major version of .NET Framework and includes support for all previous versions (including 4.5) via multi-targeting.
Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2008 R2 SP1, or Windows Server 2012.
For older enterprise projects, you can also review the Microsoft .NET Framework 4.5.1 Developer Pack via the official Microsoft Download Center.
Do not try to install the 4.5 runtime . You only need the Targeting Pack (the reference assemblies). Visual Studio will compile your app against the 4.5 rules, and your Windows 4.8 runtime will execute it flawlessly. MSBuild Error: "The target framework ... was not found"
Includes compilers, build tools, and debugging utilities. System Requirements
Because versions 4.0 through 4.5.1 are considered end-of-life, finding the direct installation source can sometimes be difficult. This comprehensive guide provides the official Microsoft .NET Framework Download Center channels and workarounds for modern IDEs. Official .NET Framework 4.5 Developer Pack Links