How to make the compiled code under 4.5 .net work on a computer with 3.5?

Question

.NET

There is a solution that works with 4.5 libraries, while when you try to compile under 3.5, put it in a folder with an executable file and add links to them, VS still swears that the platform is old and all that, and the necessary functionality in the old libraries ( working with zip and doc ) are not.
On the end device will be no higher than 3.5, what to do?
thanks in advance

Answer 1

If you need to build a project that works specifically with these libraries, try to find them for version 3.5. Rebuilding them from 4.5 to 3.5 will not work.
I once had such a case. When I downloaded from NUGet, I did not find what I needed.
I found the source code on GitHub, compiled it, and started working.