If, however, your problem is with opening a project which targets. NET 4.0 when you have a later version installed as each version is an in-place update to the last. NET 4.0, 4.5, 4.5.1, 4.5.2 and 4.6 installed and can run code targeting any of those framework versions without making any modifications to your Windows installation. NET 4.6 installed (it's part of Windows 10 so you need not manually install it) means you have.
NET Framework 4.6 is a highly compatible, in-place update to the Microsoft.
From the download page for the 'Microsoft.
