Should I remove old .NET Framework?

Infopackets Reader Dan F. writes:

" Dear Dennis,

When I run Windows Update, it tells me there are .NET Framework 3.5 updates available. Should I install these Windows Updates, even though my computer has .NET framework 4.5? Also, should I remove old .NET framework (versions 1, 2, etc) from the Windows Control Panel? Or will it cause problems? "

My response:

I recommend installing Windows Updates as soon as they are available (for the reasons I outlined in the comments section of yesterday's article), as the latest Windows Updates usually address bug fixes or security-related issues. Without installing the latest Windows Updates, your system may be exploitable and can result in malware infection, or worse.

Should I Remove Old .NET Framework?

You can remove the old versions of .NET framework on your system if you wish, but doing so comes with caveats.

Most likely you have a program already installed on your system that requires a specific version of .NET framework. If you remove the wrong .NET framework (whether it's version 1, 2, etc), some programs may no longer function. That said, newer versions of .NET framework are most likely not backwards compatible with older versions of .NET framework.

Case and point: an old program I use, "RSS Reader," requires .NET framework version 1. The author of the program did not know that the latest version of .NET framework version existed (currently version 4.5) because the program is more than a decade old, and because .NET framework version 1 was the only version available at the time. As such, this program specifically requests .NET framework version 1 during install on my system. Therefore, this particular program won't work with .NET framework 4.5, though technically it may be compatible.

If you insist on only using the newest .NET framework (for whatever reason that may be), you will have to figure out which programs use the old .NET framework and uninstall / replace them with newer programs that provide similar functionality and / or that do not require .NET framework to function.

How to know which program requires which .NET Framework?

Unfortunately there's no easy way to know which programs require which .NET (that I know of), though there may be some freeware program available that can provide this sort of detective work. If you uninstall a .NET framework and then launch a program that happens to require the .NET you just uninstalled, you will most likely receive a Windows error message stating that some sort of .DLL file is missing and that the program can't launch.

If you type in the .DLL error message into Google (example: "somefile.dll not found", or such), the search results will usually point you in the right direction. After clicking on a few pages, I'm sure you'll come across one that will tell you that you are missing .NET framework required to run the program. In that case, you can simply uninstall the broken program with a replacement.