Important
All .NET Framework versions since .NET Framework 4 are in-place updates, so only a single 4.x version can be present on a system. In addition, particular versions of the .NET Framework are pre-installed on some versions of the Windows operating system. This means that:
- If there's a later 4.x version installed on the machine already, you can't install a previous 4.x version.
- If the OS comes pre-installed with a particular .NET Framework version, you can't install a previous 4.x version on the same machine.
- If you install a later version, you don't have to first uninstall the previous version.